The ARM Building had been abnormally quiet for some months now.

We'd needed the rest -- at first. But these last few mornings the silence had had an edgy quality. We waved at each other on our paths to our respective desks, but our heads were elsewhere. Some of us had a restless look. Others were visibly, determinedly busy.

Nobody wanted to join a mother hunt.

This past year we'd managed to cut deep into the organlegging activities in the West Coast area. Pats on the back all around, but the results were predictable: other activities were going to increase. Sooner or later the newspapers would start screaming about stricter enforcement of the Fertility Laws, and then we'd all be out hunting down illegitimate parents ... all of us who were not involved in something else.

It was high time I got involved in something else.

This morning I walked to my office through the usual edgy silence. I ran coffee, carried it to my desk, punched for messages at the computer terminal. A slender file slid from the slot. A hopeful sign. I picked it up one-handed so that I could sip coffee as I went through it and let it fall open in the middle.

Color holographs jumped out at me. I was looking down through a pair of windows over two morgue tables.

_Stomach to brain: LURCH! What a hell of an hour to be looking at people with their faces burned off! Get eyes to look somewhere else and don't try to swallow that coffee. Why don't you change jobs?_

They were hideous. Two of them, a man and a woman. Something had burned their faces away down to the skulls and beyond: bones and teeth charred, brain tissue cooked.

I swallowed and kept looking. I'd seen the dead before. These had just hit me at the wrong time.

Not a laser weapon, I thought ... though that was chancy. There are thousands of jobs for lasers and thousands of varieties to do the jobs. Not a hand laser, anyway. The pencil-thin beam of a hand laser would have chewed channels in the flesh. This had been a wide, steady beam of some kind.

I flipped back to the beginning and skimmed.

Details: They'd been found on the Wilshire slidewalk in West Los Angeles around 4:30 A.M. People don't use the slidewalks that late. They're afraid of organleggers. The bodies could have travelled up to a couple of miles before anyone saw them.

Preliminary autopsy: They'd been dead three or four days. No signs of drugs or poisons or puncture marks. Apparently the burns had been the only cause of death.

It must have been quick, then: a single flash of energy. Otherwise they'd have tried to dodge, and there'd be burns elsewhere. There were none. Just the faces and char marks around the collars.

There was a memo from Bates, the coroner. From the look of them, they might have been killed by some new weapon. So he'd sent the file over to us. Could we find anything in the ARM files that would fire a blast of heat or light a foot across?

I sat back and stared into the holos and thought about it.

A light weapon with a beam a foot across? They make lasers in that size, but as war weapons, used from orbit. One of those would have vaporized the heads, not charred them.

There were other possibilities. Death by torture, with the heads held in clamps in the blast from a commercial attitude jet. Or some kind of weird industrial accident: a flash explosion that had caught them both looking over a desk or something. Or even a laser beam reflected from a convex mirror.

Forget about its being an accident. The way the bodies were abandoned reeked of guilt, of something to be covered up. Maybe Bates was right. A new illegal weapon.

And I could be deeply involved in searching for it when the mother hunt started.

* * * *

The ARM has three basic functions. We hunt organleggers. We monitor world technology: new developments that might create new weapons or that might affect the world economy or the balance of power among nations. And we enforce the Fertility Laws.

Come, let us be honest with ourselves. Of the three, protecting the Fertility Laws is probably the most important.

Organleggers don't aggravate the population problem.

Monitoring of technology is necessary enough, but it may have happened too late. There are enough fusion power plants and fusion rocket motors and fusion crematoriums and fusion seawater distilleries around to let any madman or group thereof blow up the Earth or any selected part of it.

But if a lot of people in one region started having illegal babies, the rest of the world would scream. Some nations might even get mad enough to abandon population control. Then what? We've got eighteen billion on Earth now. We couldn't handle more.

So the mother hunts are necessary. But I hate them. It's no fun hunting down some poor sick woman so desperate to have children that she'll go through hell to avoid her six-month contraceptive shots. I'll get out of it if I can.

I did some obvious things. I sent a note to Bates at the coroner's office. _Send all further details on the autopsies and let me know if the corpses are identified._ Retinal prints and brain-wave patterns were obviously out, but they might get something on gene patterns and fingerprints.

I spent some time wondering where two bodies had been kept for three to four days, and why, before being abandoned in a way that could have been used three days earlier. But that was a problem for the LAPD detectives. Our concern was with the weapon.

So I started writing a search pattern for the computer: Find me a widget that will fire a beam of a given description. From the pattern of penetration into skin and bone and brain tissue, there was probably a way to express the frequency of the light as a function of the duration of the blast, but I didn't fool with that. I'd pay for my laziness later, when the computer handed me a foot-thick list of light-emitting machinery and I had to wade through it.

I had punched in the instructions and was relaxing with more coffee and a cigarette when Ordaz called.

Detective-Inspector Julio Ordaz was a slender, dark-skinned man with straight black hair and soft black eyes. The first time I saw him in a phone screen, he had been telling me of a good friend's murder. Two years later I still flinched when I saw him.

"Hello, Julio. Business or pleasure?"

"Business, Gil. It is to be regretted."

"Yours or mine?"

"Both. There is murder involved, but there is also a machine ... Look, can you see it behind me?" Ordaz stepped out of the field of view, then reached invisibly to turn the phone camera.

I looked into somebody's living room. There was a wide circle of discoloration in the green indoor grass rug. In the center of the circle, a machine and a man's body.

Was Julio putting me on? The body was old, half-mummified. The machine was big and cryptic in shape, and it glowed with a subdued, eerie blue light.

Ordaz sounded serious enough. "Have you ever seen anything like this?"

"No. That's some machine." Unmistakably an experimental device: no neat plastic case, no compactness, no assembly-line welding. Too complex to examine through a phone camera, I decided. "Yah, that looks like something for us. Can you send it over?"

Ordaz came back on. He was smiling, barely. "I'm afraid we cannot do that. Perhaps you should send someone here to look at it."

"Where are you now?"

"In Raymond Sinclair's apartment on the top floor of the Rodewald Building in Santa Monica."

"I'll come myself," I said. My tongue suddenly felt thick.

"Please land on the roof. We are holding the elevator for examination."

"Sure." I hung up.

Raymond Sinclair!

I'd never met Raymond Sinclair. He was something of a recluse. But the ARM had dealt with him once in connection with one of his inventions, the FyreStop device. And everyone knew that he had lately been working on an interstellar drive. It was only a rumor, of course ... but if someone had killed the brain that held that secret...

I went.

* * * *

The Rodewald Building was forty stories of triangular prism with a row of triangular balconies going up each side. The balconies stopped at the thirty-eighth floor.

The roof was a garden. There were rosebushes in bloom along one edge, full-grown elms nestled in ivy along another, and a miniature forest of bonsai trees along the third. The landing pad and carport were in the center. A squad car floated down ahead of my taxi, then slid under the carport to give me room to land.

A cop in a vivid orange uniform came out to watch me come down. He was carrying a deep-sea fishing pole, still in its kit.

He said, "May I see some ID, please?"

I had my ARM ident in my hand. He checked it in the console in the squad car, then handed it back. "The inspector's waiting downstairs," he said.

"What's the pole for?"

He smiled suddenly, almost secretively. "You'll see."

We left the garden smells via a flight of concrete stairs. They led down into a small room half-full of gardening tools and a heavy door with a spy-eye in it. Ordaz opened the door for us. He shook my hand briskly, glanced at the cop. "You found something? Good."

The cop said, "There's a sporting goods store six blocks from here. The manager let me borrow it. He made sure I knew the name of the store."

"Yes, there will certainly be publicity on this matter. Come, Gil." Ordaz took my arm. "You should examine this before we turn it off."

No garden smells here, but there was something -- a whiff of something long dead -- that the air-conditioning hadn't quite cleared away. Ordaz walked me into the living room.

It looked like somebody's idea of a practical joke.

The indoor grass covered Sinclair's living room floor, wall to wall. In a perfect fourteen-foot circle between the sofa and the fireplace, the rug was brown and dead. Elsewhere it was green and thriving.

A man's mummy, dressed in stained slacks and turtleneck, lay on its back in the center of the circle. At a guess it had been about six months dead. It wore a big wristwatch with extra dials on the face and a fine-mesh platinum band, loose now around a wrist of bones and brown skin. The back of the skull had been smashed open, possibly by the classic blunt instrument lying next to it.

If the fireplace was false -- it almost had to be; nobody burns wood -- the fireplace instruments were genuine nineteenth- or twentieth-century antiques. The rack was missing a poker. A poker lay inside the circle, in the dead grass next to the disintegrating mummy.

The glowing device sat just in the center of the magic circle.

I stepped forward, and a man's voice spoke sharply. "Don't go inside that circle of rug. It's more dangerous than it looks."

It was a man I knew: Officer-One Valpredo, a tall man with a small, straight mouth and a long, narrow Italian face.

"Looks dangerous enough to me," I said.

"It is. I reached in there myself," Valpredo told me, "right after we got here. I thought I could flip the switch off. My whole arm went numb. Instantly. No feeling all. I yanked it away fast, but for a minute or so after that my whole arm was dead meat. I thought I'd lost it. Then it was all pins and needles, like I'd slept on it."

The cop who had brought me in had almost finished assembling the deep-sea fishing pole.

Ordaz waved into the circle. "Well? Have you ever seen anything like this?"

I shook my head, studying the violet-glowing machine. "Whatever it is, it's brand-new. Sinclair's really done it this time."

An uneven line of solenoids was attached to a plastic frame with homemade joins. Blistered spots on the plastic showed where other objects had been attached and later removed. A breadboard bore masses of heavy wiring. There were six big batteries hooked in parallel and a strange, heavy piece of sculpture in what we later discovered was pure silver, with wiring attached at three curving points. The silver was tarnished almost black, and there were old file marks at the edges.

Near the center of the arrangement, just in front of the silver sculpture, were two concentric solenoids embedded in a block of clear plastic. They glowed blue shading to violet. So did the batteries. A less perceptible violet glow radiated from everywhere on the machine, more intensely in the interior parts.

That glow bothered me more than anything else. It was too theatrical. It was like something a special effects man might add to a cheap late-night thriller to suggest a mad scientist's laboratory.

I moved around to get a closer look at the dead man's watch.

"Keep your head out of the field!" Valpredo said sharply. I nodded. I squatted on my heels outside the borderline of dead grass.

The dead man's watch was going like crazy. The minute hand was circling the dial every seven seconds or so. I couldn't find the second hand at all.

I backed away from the arc of dead grass and stood up. Interstellar drive, hell. This blue-glowing monstrosity looked more like a time machine gone wrong.

I studied the single-throw switch welded to the plastic frame next to the batteries. A length of nylon line dangled from the horizontal handle. It looked like someone had tugged the switch on from outside the field by using the line, but he'd have had to hang from the ceiling to tug it off that way.

"I see why you couldn't send it over to ARM Headquarters. You can't even touch it. You stick your arm or your head in there for a second, and that's ten minutes without a blood supply."

Ordaz said, "Exactly."

"It looks like you could reach in there with a stick and flip that switch off."

"Perhaps. We are about to try that." He waved at the man with the fishing pole. "There was nothing in this room long enough to reach the switch. We had to send -- "

"Wait a minute. There's a problem."

He looked at me. So did the cop with the fishing pole.

"That switch could be a self-destruct. Sinclair was supposed to be a secretive bastard. Or the field might hold considerable potential energy. Something might go blooey."

Ordaz sighed. "We must risk it. Gil, we have measured the rotation of the dead man's wristwatch. One hour per seven seconds. Fingerprints, footprints, laundry marks, residual body odor, stray eyelashes, all disappearing at an hour per seven seconds." He gestured, and the cop moved in and began trying to hook the switch.

"Already we may never know just when he was killed," Ordaz said.

The tip of the pole wobbled in large circles, steadied beneath the switch, made contact. I held my breath. The pole bowed. The switch snapped up, and suddenly the violet glow was gone. Valpredo reached into the field, warily, as if the air might be red hot. Nothing happened, and he relaxed.

Then Ordaz began giving orders, and quite a lot happened. Two men in lab coats drew a chalk outline around the mummy and the poker. They moved the mummy onto a stretcher, put the poker in a plastic bag, and put it next to the mummy.

I said, "Have you identified that?"

"I'm afraid so," Ordaz said. "Raymond Sinclair had his own autodoc -- "

"_Did_ he? Those things are expensive."

"Yes. Raymond Sinclair was a wealthy man. He owned the top two floors of this building and the roof. According to records in his 'doc, he had a new set of bud teeth implanted two months ago." Ordaz pointed to the mummy, to the skinned-back dry lips and the buds of new teeth that were just coming in.

Right. That was Sinclair.

That brain had made miracles, and someone had smashed it with a wrought-iron rod. The interstellar drive ... that glowing Goldberg device? Or had it been still inside his head?

I said, "We'll have to get whoever did it. We'll _have_ to. Even so..." Even so. No more miracles.

"We may have her already," Julio said.

I looked at him.

"There is a girl in the autodoc. We think she is Dr. Sinclair's great-niece, Janice Sinclair."

* * * *

It was a standard drugstore autodoc, a thing like a giant coffin with walls a foot thick and a headboard covered with dials and red and green lights. The girl's face was calm, her breathing shallow. Sleeping Beauty. Her arms were in the guts of the 'doc, hidden by bulky rubbery sleeves.

She was lovely enough to stop my breath. Soft brown hair showing around the electrode cap; small, perfect nose and mouth; smooth pale blue skin shot with silver threads...

That last was an evening dye job. Without it the impact of her would have been much lessened. The blue shade varied slightly to emphasize the shape of her body and the curve of her cheekbones. The silver lines varied, too, being denser in certain areas, guiding the eye in certain directions: to the tips of her breasts or across the slight swell of abdominal muscle to a lovely oval navel.

She'd paid high for that dye job. But she would be beautiful without it.

Some of the headboard lights were red. I punched for a readout and was jolted. The 'doc had been forced to amputate her right arm. Gangrene.

She was in for a hell of a shock when she woke up.

"All right," I said. "She's lost her arm. That doesn't make her a killer."

Ordaz asked, "If she were homely, would it help?"

I laughed. "You question my dispassionate judgment? Men have died for less!" Even so, I thought he could be right. There was good reason to think that the killer was now missing an arm.

"What do you think happened here, Gil?"

"Well ... any way you look at it, the killer had to want to take Sinclair's, ah, time machine with him. It's priceless, for one thing. For another, it looks like he tried to set it up as an alibi. Which means that he knew about it before he came here." I'd been thinking this through. "Say he made sure some people knew where he was a few hours before he got here. He killed Sinclair within range of the ... call it a generator. Turned it on. He figured Sinclair's own watch would tell him how much time he was gaining. Afterward he could set the watch back and leave with the generator. There'd be no way the police could tell he wasn't killed six hours earlier, or any number you like."

"Yes. But he did not do that."

"There was that line hanging from the switch. He must have turned it on from outside the field ... probably because he didn't want to sit with the body for six hours. If he tried to step outside the field after he'd turned it on, he'd bump his nose. It'd be like trying to walk through a wall, going from field time to normal time. So he turned it off, stepped out of range, and used that nylon line to turn it on again. He probably made the same mistake Valpredo did: he thought he could step back in and turn it off."

Ordaz nodded in satisfaction. "Exactly. It was very important for him -- or her -- to do that. Otherwise he would have no alibi and no profit. If he continued to try to reach into the field -- "

"Yah, he could lose the arm to gangrene. That'd be convenient for us, wouldn't it? He'd be easy to find. But look, Julio: the girl could have done the same thing to herself trying to _help_ Sinclair. He might not have been that obviously dead when she got home."

"He might even have been alive," Ordaz pointed out.

I shrugged.

"In point of fact, she came home at one-ten, in her own car, which is still in the carport. There are cameras mounted to cover the landing pad and carport. Doctor Sinclair's security was thorough. This girl was the only arrival last night. There were no departures."

"From the roof, you mean."

"Gil, there are only two ways to leave these apartments. One is from the roof, and the other is by elevator, from the lobby. The elevator is on this floor, and it was turned off. It was that way when we arrived. There is no way to override that control from elsewhere in this building."

"So someone could have taken it up here and turned it off afterward ... or Sinclair could have turned it off before he was killed ... I see what you mean. Either way, the killer has to be still here." I thought about that. I didn't like its taste. "No, it doesn't fit. How could she be bright enough to work out that alibi, then dumb enough to lock herself in with the body?"

Ordaz shrugged. "She locked the elevator before killing her uncle. She did not want to be interrupted. Surely that was sensible? After she hurt her arm, she must have been in a great hurry to reach the 'doc."

One of the red lights turned green. I was glad for that. She didn't look like a killer. I said half to myself, "Nobody looks like a killer when he's asleep."

"No. But she is where a killer ought to be. _Que lastima_."

We went back to the living room. I called ARM Headquarters and had them send a truck.

The machine hadn't been touched. While we waited, I borrowed a camera from Valpredo and took pictures of the setup in situ. The relative positions of the components might be important.

The lab men were in the brown grass, using aerosol sprays to turn fingerprints white and give a vivid yellow glow to faint traces of blood. They got plenty of fingerprints on the machine, none at all on the poker. There was a puddle of yellow in the grass where the mummy's head had been and a long yellow snail track ending at the business end of the poker. It looked like someone had tried to drag the poker out of the field after it had fallen.

Sinclair's apartments were roomy and comfortable and occupied the entire top floor. The lower floor was the laboratory where Sinclair had produced his miracles. I went through it with Valpredo. It wasn't that impressive. It looked like an expensive hobby setup. These tools would assemble components already fabricated, but they would not build anything complex.

Except for the computer terminal. That was like a little womb, with a recline chair inside a 360-degree wraparound holovision screen and enough banked controls to fly the damn thing to Alpha Centauri.

The secrets there must be in that computer! But I didn't try to use it. We'd have to send an ARM programmer to break whatever fail-safe codes Sinclair had put in the memory banks.

The truck arrived. We dragged Sinclair's legacy up the stairs to the roof in one piece. The parts were sturdily mounted on their frame, and the stairs were wide and not too steep.

I rode home in the back of the truck. Studying the generator. That massive piece of silver had something of the look of _Bird in Flight_: a triangle operated on by a topology student with wires at what were still the corners. I wondered if it was the heart of the machine or just a piece of misdirection. Was I really riding with an interstellar drive? Sinclair could have started that rumor himself to cover whatever this was. Or ... there was no law against his working two projects simultaneously.

I was looking forward to Bera's reaction.

Jackson Bera came upon us moving it through the halls of ARM Headquarters. He trailed along behind us. Nonchalant. We pulled the machine into the main laboratory and started checking it against the holos I'd taken in case something had been jarred loose. Bera leaned against the doorjamb, watching us, his eyes gradually losing interest until he seemed about to go to sleep.

I'd met him three years ago, when I had returned from the asteroids and joined the ARM. He was twenty then, and two years an ARM, but his father and grandfather had both been ARMs. Much of my training had come from Bera. And as I learned to hunt men who hunt other men, I had watched what it was doing to him.

An ARM needs empathy. He needs the ability to piece together a picture of the mind of his prey. But Bera had too much empathy. I remember his reaction when Kenneth Graham killed himself: a single surge of current through the plug in his skull and down the wire to the pleasure center of his brain. Bera had been twitchy for weeks. And the Anubis case early last year. When we realized what the man had done, Bera had been close to killing him on the spot. I wouldn't have blamed him.

Last year Bera had had enough. He'd gone into the technical end of the business. His days of hunting organleggers were finished. He was now running the ARM laboratory.

He _had_ to want to know what this oddball contraption was. I kept waiting for him to ask ... and he watched, faintly smiling. Finally it dawned on me. He thought it was a practical joke, something I'd cobbled together for his own discomfiture.

I said, "Bera."

And he looked at me brightly and said, "Hey, man, what is it?"

"You ask the most embarrassing questions."

"Right, I can understand your feeling that way, but what _is_ it? I love it, it's neat, but what is this that you have brought me?"

I told him all I knew, such as it was. When I finished, he said, "It doesn't sound much like a new space drive."

"Oho, you heard that, too, did you? No, it doesn't. Unless -- " I'd been wondering since I first saw it. "Maybe it's supposed to accelerate a fusion explosion. You'd get greater efficiency in a fusion drive."

"They get better than ninety percent now, and that widget looks _heavy_." He reached to touch the bent silver triangle gently with long, tapering fingers. "Huh. Well, we'll dig out the answers."

"Good luck. I'm going back to Sinclair's place."

"Why? The action is here." Often enough he'd heard me talking wistfully of joining an interstellar colony. He must know how I'd feel about a better drive for the interstellar slowboats.

"It's like this," I said. "We've got the generator, but we don't know anything about it. We might wreck it. I'm going to have a whack at finding someone who knows something about Sinclair's generator."

"Meaning?"

"Whoever tried to steal it. Sinclair's killer."

"If you say so." But he looked dubious. He knew me too well. He said, "I understand there's a mother hunt in the offing."

"Oh?"

He smiled. "Just a rumor. You guys are lucky. When my dad first joined, the business of the ARM was _mostly_ mother hunts. The organleggers hadn't really got organized yet, and the Fertility Laws were new. If we hadn't enforced them, nobody would have obeyed them at all."

"Sure, and people threw rocks at your father. Bera, those days are _gone_."

"They could come back. Having children is basic."

"Bera, I did not join the ARM to hunt unlicensed parents." I waved and left before he could answer. I could do without the call to duty from Bera, who had done with hunting men and mothers.

* * * *

I'd had a good view of the Rodewald Building while dropping toward the roof this morning. I had a good view now from my commandeered taxi. This time I was looking for escape paths.

There were no balconies on Sinclair's floors, and the windows were flush to the side of the building. A cat burglar would have trouble with them. They didn't look like they'd open.

I tried to spot the cameras Ordaz had mentioned as the taxi dropped toward the roof. I couldn't find them. Maybe they were mounted in the elms.

Why was I bothering? I hadn't joined the ARM to chase mothers or machinery or common murderers.

I'd joined the ARM to hunt organleggers.

The ARM doesn't deal in murder per se. The machine was out of my hands now. A murder investigation wouldn't keep me out of a mother hunt. And I'd never met the girl. I knew nothing of her beyond the fact that she was where a killer ought to be.

Was it just that she was pretty?

Poor Janice. When she woke up ... For a solid month I'd wakened to that same stunning shock, the knowledge that my right arm was gone.

The taxi settled. Valpredo was waiting below.

I speculated ... Cars weren't the only things that flew. But anyone flying one of those tricky ducted-fan flycycles over a city, where he could fall on a pedestrian, wouldn't have to worry about a murder charge. They'd feed him to the organ banks regardless. And anything that flew would leave traces anywhere but on the landing pad itself. It would crush a rosebush or a bonsai tree or be flipped over an elm.

The taxi took off in a whisper of air.

Valpredo was grinning at me. "The thinker. What's on your mind?"

"I was wondering if the killer could have come down on the carport roof."

He turned to study the situation. "There are two cameras mounted on the edge of the roof. If his vehicle was light enough, sure, he could land there, and the cameras wouldn't spot him. Roof wouldn't hold a car, though. Anyway, nobody did it."

"How do you know?"

"I'll show you. By the way, we inspected the camera system. We're pretty sure the cameras weren't tampered with. Nobody even landed here until seven this morning. Look here." We had reached the concrete stairs that led down into Sinclair's apartments. Valpredo pointed at a glint of light in the sloping ceiling, at heart level. "This is the only way down. The camera would get anyone coming in or out. It might not catch his face, but it'd show if someone passed. It takes sixty frames a minute."

I went on down. A cop let me in.

Ordaz was on the phone. The screen showed a young man with a deep tan and shock showing through the tan. Ordaz waved at me, a shushing motion, and went on talking. "Fifteen minutes? That will be a great help to us. Please land on the roof. We are still working on the elevator."

He hung up and turned to me. "Andrew Porter, Janice Sinclair's lover. He tells us that he and Janice spent the evening at a party. She dropped him off at his home around one o'clock."

"Then she came straight home, if that's her in the 'doc."

"I think it must be. Mr. Porter says she was wearing a blue skin-dye job." Ordaz was frowning. "He put on a most convincing act, if it was that. I think he really was not expecting any kind of trouble. He was surprised that a stranger answered, shocked when he learned of Doctor Sinclair's death, and horrified when he learned that Janice had been hurt."

With the mummy and the generator removed, the murder scene had become an empty circle of brown grass marked with random streaks of yellow chemical and outlines of white chalk.

"We had some luck," Ordaz said. "Today's date is June 4, 2124. Dr. Sinclair was wearing a calendar watch. It registered January 17, 2125. If we switched the machine off at ten minutes to ten -- which we did -- and if it was registering an hour for every seven seconds that passed outside the field, then the field must have gone on at around one o'clock last night, give or take a margin of error."

"Then if the girl didn't do it, she must have just missed the killer."

"Exactly."

"What about the elevator? Could it have been jiggered?"

"No. We took the workings apart. It was on this floor and locked by hand. Nobody could have left by elevator..."

"Why did you trail off like that?"

Ordaz shrugged, embarrassed. "This peculiar machine really does bother me, Gil. I found myself thinking, Suppose it can reverse time? Then the killer could have gone down in an elevator that was going up."

He laughed with me. I said, "In the first place, I don't believe a word of it. In the second place, he didn't have the machine to do it with. Unless ... he made his escape before the murder. Dammit, now you've got me doing it."

"I would like to know more about the machine."

"Bera's investigating it now. I'll let you know as soon as we learn anything. And _I'd_ like to know more about how the killer couldn't possibly have left."

He looked at me. "Details?"

"Could someone have opened a window?"

"No. These apartments are forty years old. The smog was still bad when they were built. Dr. Sinclair apparently preferred to depend on his air-conditioning."

"How about the apartment below? I presume it has a different set of elevators."

"Yes, of course. It belongs to Howard Rodewald, the owner of this building -- of this chain of buildings, in fact. At the moment he is in Europe. His apartment has been loaned to friends."

"There's no stairs down to there?"

"No. We searched these apartments thoroughly."

"All right. We know the killer had a nylon line, because he left a strand of it on the generator. Could he have climbed down to Rodewald's balcony from the roof?"

"Thirty feet? Yes, I suppose so." Ordaz's eyes sparked. "We must look into that. There is still the matter of how he got past the camera and whether he could have gotten inside once he was on the balcony."

"Yah."

"Try this, Gil. Another question. How did he _expect_ to get away?" He watched for my reaction, which must have been satisfying, because it _was_ a damn good question. "You see, if Janice Sinclair murdered her great-uncle, then neither question applies. If we are looking for someone else, we have to assume that his plans misfired. He had to improvise."

"Uh huh. He could still have been planning to use Rodewald's balcony. And that would mean he had a way past the camera..."

"Of course he did. The generator."

Right. If he came to steal the generator ... and he'd have to steal it regardless, because if we found it here, it would shoot his alibi sky high. So he'd leave it on while he trundled it up the stairs. Say it took him a minute; that's only an eighth of a second of normal time. One chance in eight that the camera would fire, and it would catch nothing but a streak ... "Uh oh."

"What is it?"

"He had to be planning to steal the machine. Is he really going to lower it to Rodewald's balcony by _rope_?"

"I think it unlikely," Ordaz said. "It weighed more than fifty pounds. He could have moved it upstairs. The frame would make it portable. But to lower it by rope..."

"We'd be looking for one hell of an athlete."

"At least you will not have to search far to find him. We assume that your hypothetical killer came by elevator, do we not?"

"Yah." Nobody but Janice Sinclair had arrived by the roof last night.

"The elevator was programmed to allow a number of people to enter it and to turn away all others. The list is short. Doctor Sinclair was not a gregarious man."

"You're checking them out? Whereabouts, alibis, and so forth?"

"Of course."

"There's something else you might check on," I said. But Andrew Porter came in, and I had to postpone it.

Porter came casual, in a well-worn translucent one-piece jumpsuit he must have pulled on while running for a taxi. The muscles rolled like boulders beneath the loose fabric, and his belly muscles showed like the plates on an armadillo. Surfing muscles. The sun had bleached his hair nearly white and burned him as brown as Jackson Bera. You'd think a tan that dark would cover for blood draining out of a face, but it doesn't.

"Where is she?" he demanded. He didn't wait for an answer. He knew where the 'doc was, and he went there. We trailed in his wake.

Ordaz didn't push. He waited while Porter looked down at Janice, then punched for a readout and went through it in detail. Porter seemed calmer then, and his color was back. He turned to Ordaz and said, "What happened?"

"Mr. Porter, did you know anything of Dr. Sinclair's latest project?"

"The time compressor thing? Yah. He had it set up in the living room when I got here yesterday evening -- right in the middle of that circle of dead grass. Any connection?"

"When did you arrive?"

"Oh, about six. We had some drinks, and Uncle Ray showed off his machine. He didn't tell us much about it. Just showed what it could do." Porter showed us flashing white teeth. "It _worked_. That thing can compress time! You could live your whole life in there in two months! Watching him move around inside the field was like trying to keep track of a hummingbird. Worse. He struck a match -- "

"When did you leave?"

"About eight. We had dinner at Cziller's House of Irish Coffee, and -- Listen, what _happened_ here?"

"There are some things we need to know first, Mr. Porter. Were you and Janice together for all of last evening? Were there others with you?"

"Sure. We had dinner alone, but afterward we went to a kind of party. On the beach at Santa Monica. Friend of mine has a house there. I'll give you the address. Some of us wound up back at Cziller's around midnight. Then Janice flew me home."

"You have said that you are Janice's lover. Doesn't she live with you?"

"No. I'm her steady lover, you might say, but I don't have any strings on her." He seemed embarrassed. "She lives here with Uncle Ray. Lived. Oh, _hell_." He glanced

into the 'doc. "Look, the readout said she'll be waking up any minute. Can I get her a robe?"

"Of course."

We followed Porter to Janice's bedroom, where he picked out a peach-colored negligee for her. I was beginning to like the guy. He had good instincts. An evening dye job was not the thing to wear on the morning of a murder. And he'd picked one with long, loose sleeves. Her missing arm wouldn't show so much.

"You call him Uncle Ray," Ordaz said.

"Yah. Because Janice did."

"He did not object? Was he gregarious?"

"Gregarious? Well, no, but _we_ liked each other. We both liked puzzles, you understand? We traded murder mysteries and jigsaw puzzles. Listen, this may sound silly, but are you sure he's dead?"

"Regrettably, yes. He is dead, and murdered. Was he expecting someone to arrive after you left?"

"Yes."

"He said so?"

"No. But he was wearing a shirt and pants. When it was just us, he usually went naked."

"Ah."

"Older people don't do that much," Porter said. "But Uncle Ray was in good shape. He took care of himself."

"Have you any idea whom he might have been expecting?"

"No. Not a woman; not a date, I mean. Maybe someone in the same business."

Behind him, Janice moaned.

Porter was hovering over her in a flash. He put a hand on her shoulder and urged her back. "Lie still, love. We'll have you out of there in a jiffy."

She waited while he disconnected the sleeves and other paraphernalia. She said, "What happened?"

"They haven't told me yet," Porter said with a flash of anger. "Be careful sitting up. You've had an accident."

"What kind of -- ? _Oh!_"

"It'll be all right."

"My _arm_!"

Porter helped her out of the 'doc. Her arm ended in pink flesh two inches below the shoulder. She let Porter drape the robe around her. She tried to fasten the sash, quit when she realized she was trying to do it with one hand.

I said, "Listen, I lost my arm once."

She looked at me. So did Porter.

"I'm Gil Hamilton. With the UN Police. You really don't have anything to worry about. See?" I raised my right arm, opened and closed the fingers. "The organ banks don't get much call for arms. You probably won't even have to wait. I didn't. It feels just like the arm I was born with, and it works just as well."

"How did you lose it?" she asked.

"Ripped away by a meteor," I said.

Ordaz said to her, "Do you remember how you lost your own arm?"

"Yes." She shivered. "Could we go somewhere where I could sit down? I feel a bit weak."

We moved to the living room. Janice dropped onto the couch a bit too hard. It might have been shock, or the missing arm might be throwing her balance off. I remembered. She said, "Uncle Ray's dead, isn't he?"

"Yes."

"I came home and found him that way. Lying next to that time machine of his, and the back of his head all bloody. I thought maybe he was still alive, but I could see the machine was going; it had that violet glow. I tried to get hold of the poker. I wanted to use it to switch the machine off, but I couldn't get a grip. My arm wasn't just numb; it wouldn't move. You know, you can try to wiggle your toes when your foot's asleep, but ... I could get my hands on the handle of the damn poker, but when I tried to pull, it just slid off."

"You kept trying?"

"For a while. Then ... I backed away to think it over. I wasn't about to waste any time with Uncle Ray maybe dying in there. My arm felt stone dead ... I guess it was, wasn't it?" She shuddered. "Rotting meat. It smelled that way. And all of a sudden I felt so weak and dizzy, like was dying myself. I barely made it into the 'doc."

"Good thing you did," I said. The blood was leaving Porter's face again as he realized what a close thing it had been.

Ordaz said, "Was your great-uncle expecting visitors last night?"

"I think so."

"Why do you think so?"

"I don't know. He just -- acted that way."

"We are told that you and some friends reached Cziller's House of Irish Coffee around midnight. Is that true?"

"I guess so. We had some drinks, then I took Drew home and came home myself."

"Straight home?"

"Yes." She shivered. "I put the car away and went downstairs. I knew something was wrong. The door was open. Then there was Uncle Ray lying next to that machine! I knew better than to just run up to him. He'd told us not to step into the field."

"Oh? Then you should have known better than to reach for the poker."

"Well, yes. I could have used the tongs," she said as if the idea had just occurred to her. "It's just as long. I didn't think of it. There wasn't _time_. Don't you understand? He was dying in there, or dead!"

"Yes, of course. Did you interfere with the murder scene in any way?"

She laughed bitterly. "I suppose I moved the poker about two inches. Then, when I felt what was happening to me, I just ran for the 'doc. It was awful. Like dying."

"Instant gangrene," Porter said.

Ordaz said, "You did not, for example, lock the elevator?"

Damn! I should have thought of that.

"No. We usually do when we lock up for the night, but I didn't have time."

Porter said, "Why?"

"The elevator was locked when we arrived," Ordaz told

Porter ruminated that. "Then the killer must have left by the roof. You'll have pictures of him."

Ordaz smiled apologetically. "That is our problem. No cars left the roof last night. Only one car arrived. That was yours, Miss Sinclair."

"But," Porter said, and he stopped.

"What happened was this," Ordaz said. "Around five-thirty this morning, the tenants in -- " He stopped to remember. " -- in 36A called the building maintenance man about a smell as of rotting meat coming through the air-conditioning system. He spent some time looking for the source, but once he reached the roof, it was obvious. He -- "

Porter pounced. "He reached the roof in what kind of vehicle?"

"Mr. Steeves says that he took a taxi from the street. There is no other way to reach Dr. Sinclair's private landing pad, is there?"

"No. But why would he do that?"

"Perhaps there have been other times when strange smells came from Dr. Sinclair's laboratory. We will ask him."

"Do that."

"Mr. Steeves followed the smell through the doctor's open door. He called us. He waited for us on the roof."

"What about his taxi?" Porter was hot on the scent. "Maybe the killer just waited till that taxi got here, then took it somewhere else when Steeves finished with it."

"It left immediately after Steeves had stepped out. He had a taxi clicker if he wanted another. The cameras were on it the entire time it was on the roof." Ordaz paused. "You see the problem?"

Apparently Porter did. He ran both hands through his white-blond hair. "I think we ought to put off discussing it until we know more."

He meant Janice. Janice looked puzzled; she hadn't caught on. But Ordaz nodded at once and stood up. "Very well. There is no reason Miss Sinclair cannot go on living here. We may have to bother you again," he told her. "For now, our condolences."

He made his exit. I trailed along. So, unexpectedly, did Drew Porter. At the top of the stairs he stopped Ordaz with a big hand around the inspector's upper arm. "You're thinking Janice did it, aren't you?"

Ordaz sighed. "I must consider the possibility."

"She didn't have any reason. She loved Uncle Ray. She's lived with him on and off these past twelve years. She hasn't got the slightest reason to kill him."

"Is there no inheritance?"

His expression went sour. "All right, _yes_, she'll have some money coming. But Janice wouldn't care about anything like that!"

"Ye-es. Still, what choice have I? Everything we now know tells us that the killer could not have left the scene of the killing. We searched the premises immediately. There was only Janice Sinclair and her murdered uncle."

Porter bit back an answer, chewed it ... He must have been tempted. Amateur detective, one step ahead of the police all the way. Yes, Watson, these gendarmes have a talent for missing the obvious ... But he had too much to lose. Porter said, "And the maintenance man. Steeves."

Ordaz lifted one eyebrow. "Yes, of course. We shall have to investigate Mr. Steeves."

"How did he get that call from, uh, 36A? Bedside phone or pocket phone? Maybe he was already on the roof."

"I don't remember what he said. But we have pictures of his taxi landing."

"He had a taxi clicker. He could have just called it down."

"One more thing," I said, and Porter looked at me hopefully. "Porter, the elevator wouldn't take anyone up unless they were on its list."

"Or unless Uncle Ray buzzed down. There's an intercom in the lobby. But at that time of night he probably wouldn't let anyone up unless he was expecting him."

"So if Sinclair was expecting a business associate, he or she was probably in the tape. How about going down? Would the elevator take you down to the lobby if you weren't in the tape?"

"I'd ... think so."

"It would," Ordaz said. "The elevator screens entrances, not departures."

"Then why didn't the killer use it? I don't mean Steeves necessarily. I mean _anyone_, whoever it might have been. Why didn't he just go down in the elevator? Whatever he did do, that had to be easier."

They looked at each other, but they didn't say anything.

"Okay." I turned to Ordaz. "When you check out the people in the tape, see if any of them shows a damaged arm. The killer might have pulled the same stunt Janice did: ruined her arm trying to turn off the generator. And I'd like a look at who's in that tape."

"Very well," Ordaz said, and we moved toward the squad car under the carport. We were out of earshot when he added, "How does the ARM come into this, Mr. Hamilton? Why your interest in the murder aspect of this case?"

I told him what I'd told Bera: that Sinclair's killer might be the only living expert on Sinclair's time machine. Ordaz nodded. What he'd really wanted to know was: Could I justify giving orders to the Los Angeles Police Department in a local matter? And I had answered yes.

* * * *

The rather simple-minded security system in Sinclair's elevator had been built to remember the thumbprints and the facial bone structures (which it scanned by deep radar, thus avoiding the problems raised by changing beard styles and masquerade parties) of up to a hundred people. Most people know about a hundred people, plus or minus ten or so. But Sinclair had only listed a dozen, including himself.

RAYMOND SINCLAIR

ANDREW PORTER

JANICE SINCLAIR

EDWARD SINCLAIR, SR.

EDWARD SINCLAIR, III

HANS DRUCKER

GEORGE STEEVES

PAULINE URTHIEL

BERNATH PETERFI

LAWRENCE MUHAMMAD ECKS

BERTHA HALL

MURIEL SANDUSKY

Valpredo had been busy. He'd been using the police car and its phone setup as an office while he guarded the roof. "We know who some of these are," he said. "Edward Sinclair Third, for instance, is Edward Senior's grandson, Janice's brother. He's in the Belt, in Ceres, making something of a name for himself as an industrial designer. Edward Senior is Raymond's brother. He lives in Kansas City. Hans Drucker and Bertha Hall and Muriel Sandusky all live in the Greater Los Angeles area; we don't know what their connection with Sinclair is. Pauline Urthiel and Bernath Peterfi are technicians of sorts. Ecks is Sinclair's patent attorney."

"I suppose we can interview Edward Third by phone." Ordaz made a face. A phone call to the Belt wasn't cheap. "These others -- "

I said, "May I make a suggestion?"

"Of course."

"Send me along with whoever interviews Ecks and Peterfi and Urthiel. They probably knew Sinclair in a business sense, and having an ARM along will give you a little more clout to ask a little more detailed questions."

"I could take those assignments," Valpredo volunteered.

"Very well." Ordaz still looked unhappy. "If this list were exhaustive, I would be grateful. What if Doctor Sinclair's visitor simply used the intercom in the lobby and asked to be let in?"

* * * *

Bernath Peterfi wasn't answering his phone.

We got Pauline Urthiel via her pocket phone. A brusque contralto voice, no picture. We'd like to talk to her in connection with a murder investigation; would she be at home this afternoon? No. She was lecturing that afternoon but would be home around six.

Ecks answered dripping wet and not smiling. So sorry to get you out of a shower, Mr. Ecks. We'd like to talk to you in connection with a murder investigation.

"Sure, come on over. Who's dead?"

Valpredo told him.

"Sinclair? _Ray_ Sinclair? You're sure?"

We were.

"Oh, lord. Listen, he was working on something important. An interstellar drive, if it works out. If there's any possibility of salvaging the hardware -- "

I reassured him and hung up. If Sinclair's patent attorney thought it was a star drive ... maybe it was.

"Doesn't sound like he's trying to steal it," Valpredo said.

"No. And even if he'd got the thing, he couldn't have claimed it was his. If he's the killer, that's not what he was after."

We were moving at high speed, police-car speed. The car was on automatic, of course, but it could need manual override at any instant. Valpredo concentrated on the passing scenery and spoke without looking at me.

"You know, you and the detective-inspector aren't looking for the same thing."

"I know. I'm looking for a hypothetical killer. Julio's looking for a hypothetical visitor. It could be tough to prove there wasn't one, but if Porter and the girl were telling the truth, maybe Julio can prove the visitor didn't do it."

"Which would leave the girl," he said.

"Whose side are you on?"

"Nobody's. All I've got is interesting questions." He looked at me sideways. "But you're pretty sure the girl didn't do it."

"Yah."

"Why?"

"I don't know. Maybe because I don't think she's got the brains. It wasn't a simple killing."

"She's Sinclair's niece. She can't be a complete idiot."

"Heredity doesn't work that way. Maybe I'm kidding myself. Maybe it's her arm. She's lost an arm; she's got enough to worry about." And I borrowed the car phone to dig into records in the ARM computer.

PAULINE URTHIEL. Born Paul Urthiel. Ph.D. in plasma physics, University of California at Irvine. Sex change and legal name change, 2111. Six years ago she'd been in competition for a Nobel prize for research into the charge suppression effect in the Slaver disintegrator. Height: 5' 9". Weight: 135. Married Lawrence Muhammad Ecks, 2117. Had kept her (loosely speaking) maiden name. Separate residences.

BERNATH PETERFI. Ph.D. in subatomics and related fields, MIT. Diabetic. Height: 5' 8". Weight: 145. Application for exemption to the Fertility Laws denied, 2119. Married 2118, divorced 2122. Lived alone.

LAWRENCE MUHAMMAD ECKS. Master's degree in physics. Member of the bar. Height: 6' 1". Weight: 190. Artificial left arm. Vice president, CET (Committee to End Transplants).

Valpredo said: "Funny how the human arm keeps cropping up in this case."

"Yah." Including one human ARM who didn't really belong there. "Ecks has a master's. Maybe he could have talked people into thinking the generator was his. Or maybe he thought he could."

"He didn't try to snow _us_."

"Suppose he blew it last night? He wouldn't necessarily want the generator lost to humanity, now, would he?"

"How did he get out?"

I didn't answer.

* * * *

Ecks lived in a tapering tower almost a mile high. At one time Lindstetter's Needle must have been the biggest thing ever built, before they started with the arcologies. We landed on a pad a third of the way up, then took a drop shaft ten floors down.

He was dressed when he answered the door in blazing yellow pants and a net shirt. His skin was very dark, and his hair was a puffy black dandelion with threads of gray in it. On the phone screen I hadn't been able to tell which arm was which, and I couldn't now. He invited us in, sat down, and waited for the questions.

Where was he last night? Could he produce an alibi? It would help us considerably.

"Sorry, nope. I spent the night going through a rather tricky case. You wouldn't appreciate the details."

I told him I would. He said, "Actually, it involves Edward Sinclair -- Ray's great-nephew. He's a Belt immigrant, and he's done an industrial design that could be adapted to Earth. Swivel for a chemical rocket motor. The trouble is, it's not _that_ different from existing designs, it's just _better_. His Belt patent is good, but the UN laws are different. You wouldn't believe the legal tangles."

"Is he likely to lose out?"

"No, it just might get sticky if a firm called FireStorm decides to fight the case. I want to be ready for that. In a pinch I might even have to call the kid back to Earth. I'd hate to do that, though. He's got a heart condition."

Had he made any phone calls, say, to a computer, during his night of research?

Ecks brightened instantly. "Oh, sure. Constantly, all night. Okay, I've got an alibi."

No point in telling him that such calls could have been made from anywhere. Valpredo asked, "Do you have any idea where your wife was last night?"

"No, we don't live together. She lives three hundred stories over my head. We've got an open marriage ... maybe too open," he added wistfully.

There seemed a good chance that Raymond Sinclair was expecting a visitor last night. Did Ecks have any idea -- ?

"He knew a couple of women," Ecks said. "You might ask them. Bertha Hall is about eighty, about Ray's age. She's not too bright, not by Ray's standards, but she's as much of a physical fitness nut as he is. They go backpacking, play tennis, maybe sleep together, maybe not. I can give you her address. Then there's Muriel something. He had a crush on her a few years ago. She'd be thirty now. I don't know if they still see each other or not."

Did Sinclair know other women?

Ecks shrugged.

Who did he know professionally?

"Oh, lord, that's an endless list. Do you know anything about the way Ray worked?" He didn't wait for an answer. "He used computer setups mostly. Any experiment in his field was likely to cost millions or more. What he was good at was setting up a computer analogue of an experiment that would tell him what he wanted to know. Take, oh ... I'm sure you've heard of the Sinclair molecule chain."

Hell, yes. We used it for towing in the Belt; nothing else was light enough and strong enough. A loop of it was nearly invisibly fine, but it would cut steel.

"He didn't start working with chemicals until he was practically finished. He told me he spent four years doing molecular designs by computer analogue. The tough part was the ends of the molecule chain. Until he got that, the chain would start disintegrating from the end points the minute you finished making it. When he finally had what he wanted, he hired an industrial chemical lab to make it for him.

"That's what I'm getting at," Ecks continued. "He hired other people to do the concrete stuff once he knew what he had. And the people he hired had to know what they were doing. He knew the top physicists and chemists and field theorists everywhere on Earth and in the Belt."

Like Pauline? Like Bernath Peterfi?

"Yah, Pauline did some work for him once. I don't think she'd do it again. She didn't like having to give him all the credit. She'd rather work for herself. I don't blame her."

Could he think of anyone who might want to murder Raymond Sinclair?

Ecks shrugged. "I'd say that was your job. Ray never liked splitting the credit with anyone. Maybe someone he worked with nursed a grudge. Or maybe someone was trying to steal this latest project of his. Mind you, I don't know much about what he was trying to do, but if it worked, it would have been fantastically valuable, and not just in money."

Valpredo was making noises like he was about finished. I said, "Do you mind if I ask a personal question?"

"Go ahead."

"Your arm. How'd you lose it?"

"Born without it. Nothing in my genes, just a bad prenatal situation. I came out with an arm and a turkey wishbone. By the time I was old enough for a transplant, I knew I didn't want one. You want the standard speech?"

"No, thanks, but I'm wondering how good your artificial arm is. I'm carrying a transplant myself."

Ecks looked me over carefully for signs of moral degeneration. "I suppose you're also one of those people who keep voting the death penalty for more and more trivial offenses?"

"No, I -- "

"After all, if the organ banks ran out of criminals, you'd be in trouble. You might have to live with your mistakes."

"No, I'm one of those people who blocked the second corpsicle law, kept that group from going into the organ banks. And I hunt organleggers for a living. But I don't have an artificial arm, and I suppose the reason is that I'm squeamish."

"Squeamish about being part mechanical? I've heard of that," Ecks said. "But you can be squeamish the other way, too. What there is of me is all me, not part of a dead man. I'll admit the sense of touch isn't quite the same, but it's just as good. And -- look."

He put a hand on my upper forearm and squeezed. It felt like the bones were about to give. I didn't scream, but it took an effort. "That isn't all my strength," he said. "And I could keep it up all day. This arm doesn't get tired."

He let go.

I asked if he would mind my examining his arms. He didn't. But then, Ecks didn't know about my imaginary hand.

I probed the advanced plastics of Ecks's false arm, the bone and muscle structure of the other. It was the real arm I was interested in.

When we were back in the car, Valpredo said, "Well?"

"Nothing wrong with his real arm," I said. "No scars."

Valpredo nodded.

But the bubble of accelerated time wouldn't hurt plastic and batteries, I thought. And if he'd been planning to lower fifty pounds of generator two stories down on a nylon line, his artificial arm had the strength for it.

* * * *

We called Peterfi from the car. He was in. He was a small man, dark-complected, mild of face, his hair straight and shiny black around a receding hairline. His eyes blinked and squinted as if the light were too bright, and he had the scruffy look of a man who has slept in his clothes. I wondered if we had interrupted an afternoon nap.

Yes, he would be glad to help the police in a murder investigation.

Peterfi's condominium was a slab of glass and concrete set on a Santa Monica cliff face. His apartment faced the sea. "Expensive, but worth it for the view," he said, showing us to chairs in the living room. The drapes were closed against the afternoon sun. Peterfi had changed clothes. I noticed the bulge in his upper left sleeve where an insulin capsule and automatic feeder had been anchored to the bone of the arm.

"Well, what can I do for you? I don't believe you mentioned who had been murdered."

Valpredo told him

He was shocked. "Oh, my. Ray Sinclair. But there's no telling how this will affect -- " and he stopped suddenly.

"Please go on," said Valpredo.

"We were working on something together. Something revolutionary."

"An interstellar drive?"

He was startled. He debated with himself, then said, "Yes. It was supposed to be secret."

We admitted to having seen the machine in action. How did a time compression field serve as an interstellar drive?

"That's not exactly what it is," Peterfi said. Again he debated with himself. Then, "There have always been a few optimists around who thought that just because mass and inertia have always been associated in human experience, it need not be a universal law. What Ray and I have done is to create a condition of low inertia You see -- "

"An inertialess drive!"

Peterfi nodded vigorously at me. "Essentially yes. Is the machine intact? If not -- "

I reassured him on that point.

"That's good. I was about to say that if it had been destroyed, I could recreate it. I did most of the work of building it. Ray preferred to work with his mind, not with his hands."

Had Peterfi visited Sinclair last night?

"No. I had dinner at a restaurant down the coast, then came home and watched the holo wall. What times do I need alibis for?" he asked jokingly.

Valpredo told him. The joking look turned into a nervous grimace. No, he'd left the Mail Shirt just after nine; he couldn't prove his whereabouts after that time.

Had he any idea who might have wanted to murder Raymond Sinclair?

Peterfi was reluctant to make outright accusations. Surely we understood. It might be someone he had worked with in the past or someone he'd insulted. Ray thought most of humanity were fools. Or we might look into the matter of Ray's brother's exemption.

Valpredo said, "Edward Sinclair's exemption? What about it?"

"I'd really prefer that you get the story from someone else. You may know that Edward Sinclair was refused the right to have children because of an inherited heart condition. His grandson has it, too. There is some question as to whether he really did the work that earned him the exemption."

"But that must have been forty to fifty years ago. How could it figure in a murder now?"

Peterfi explained patiently. "Edward had a child by virtue of an exemption to the Fertility Laws. Now there are two grandchildren. Suppose the matter came up for review? His grandchildren would lose the right to have children. They'd be illegitimate. They might even lose the right to inherit."

Valpredo was nodding. "Yah. We'll look into that, all right."

I said, "You applied for an exemption yourself not long ago. I suppose your, uh -- "

"Yes, my diabetes. It doesn't interfere with my life at all. Do you know how long we've been using insulin to handle diabetes? Almost two hundred years! What does it matter if I'm a diabetic? If my children are?"

He glared at us, demanding an answer. He got none.

"But the Fertility Laws refuse me children. Do you know that I lost my wife because the board refused me an exemption? I deserved it. My work on plasma flow in the solar photosphere -- Well, I'd hardly lecture you on the subject, would I? But my work can be used to predict the patterns of proton storms near any G-type star. Every colony world owes something to my work!"

That was an exaggeration, I thought. Proton storms afflicted mainly asteroidal mining operations. "Why don't you move to the Belt?" I asked. "They'd honor you for your work, and they don't have Fertility Laws."

"I get sick off Earth. It's biorhythms; it has nothing to do with diabetes. Half of humanity suffers from biorhythm upset."

I felt sorry for the guy. "You could still get the exemption. For your work on the inertialess drive. Wouldn't that get you your wife back?"

"I ... don't know. I doubt it. It's been two years. In any case, there's no telling which way the board will jump. I thought I'd have the exemption last time."

"Do you mind if I examine your arms?"

He looked at me. "What?"

"I'd like to examine your arms."

"That seems a most curious request. Why?"

"There seems a good chance that Sinclair's killer damaged his arm last night. Now, I'll remind you that I'm acting in the name of the UN Police. If you've been hurt by the side effects of a possible space drive, one that might be used by human colonists, then you're concealing evidence in a -- " I stopped, because Peterfi had stood up and was taking off his tunic.

He wasn't happy, but he stood still for it. His arms looked all right. I ran my hands along each arm, bent the joints, massaged the knuckles. Inside the flesh I ran my imaginary fingertips along the bones.

Three inches below the shoulder joint the bone was knotted. I probed the muscles and tendons...

"Your right arm is a transplant," I said. "It must have happened about six months ago."

He bridled. "You may not be aware of it, but surgery to reattach my own arm would show the same scars."

"Is that what happened?"

Anger made his speech more precise. "Yes. I was performing an experiment, and there was an explosion. The arm was nearly severed. I tied a tourniquet and got to a 'doc before I collapsed."

"Any proof of this?"

"I doubt it. I never told anyone of this accident, and the 'doc wouldn't keep records. In any case, I think the burden of proof would be on you."

"Uh huh."

Peterfi was putting his tunic back on. "Are you quite finished here? I'm deeply sorry for Ray Sinclair's death, but I don't see what it could possibly have to do with my stupidity of six months ago."

I didn't, either. We left.

Back in the car. It was seventeen-twenty; we could pick up a snack on the way to Pauline Urthiel's place. I told Valpredo, "I think it was a transplant. And he didn't want to admit it. He must have gone to an organlegger."

"Why would he do that? It's not that tough to get an arm from the public organ banks."

I chewed that. "You're right. But if it was a normal transplant, there'll be a record. Well, it could have happened the way he said it did."

"Uh huh."

"How about this? He was doing an experiment, and it was illegal. Something that might cause pollution in a city or even something to do with radiation. He picked up radiation burns in his arm. If he'd gone to the public organ banks, he'd have been arrested."

"That would fit too. Can we prove it on him?"

"I don't know. I'd like to. He might tell us how to find whoever he dealt with. Let's do some digging: maybe we can find out what he was working on six months ago."

* * * *

Pauline Urthiel opened the door the instant we rang. "Hi! I just got in myself. Can I make you drinks?"

We refused. She ushered us into a smallish apartment with a lot of fold-into-the-ceiling furniture. A sofa and coffee table were showing now; the rest existed as outlines on the ceiling. The view through the picture window was breathtaking. She lived near the top of Lindstetter's Needle, some three hundred stories up from her husband.

She was tall and slender, with a facial structure that would have been effeminate on a man. On a woman it was a touch masculine. The well-formed breasts might be flesh or plastic but were surgically implanted in either case.

She finished making a large drink and joined us on the couch. And the questions started.

Had she any idea who might have wanted Raymond Sinclair dead?

"Not really. How did he die?"

"Someone smashed in his skull with a poker," Valpredo said. If he wasn't going to mention the generator, neither was I.

"How quaint." Her contralto turned acid. "His own poker, too, I presume. Out of his own fireplace rack. What you're looking for is a traditionalist." She peered at us over rim of her glass. Her eyes were large, the lids decorated in semipermanent tattoos as a pair of flapping UN flags. "That doesn't help much, does it? You might try whoever was working with him on whatever his latest project was."

That sounded like Peterfi, I thought. But Valpredo said, "Would he necessarily have a collaborator?"

"He generally works alone at the beginning. But somewhere along the line he brings in people to make the hardware. He never made anything real by himself. It was all just something in a computer bank. It took someone else to make it real. And he never gave credit to anyone."

Then his hypothetical collaborator might have found out how little credit he was getting for his work, and -- But Urthiel was shaking her head. "I'm talking about a psychotic, not someone who's really been cheated. Sinclair never _offered_ anyone a share in anything he did. He always made it damn plain what was happening. I knew what I was doing when I set up the FyreStop prototype for him, and I knew what I was doing when I quit. It was all him. He was using my training, not my brain. I wanted to do something original, something _me_."

Did she have any idea what Sinclair's present project was?

"My husband would know. Larry Ecks, lives in this same building. He's been dropping cryptic hints, and when I want more details, he has this grin -- " She grinned herself suddenly. "You'll gather I'm interested. But he won't say."

Time for me to take over or we'd never get certain questions asked. "I'm an ARM. What I'm about to tell you is secret," I said. And I told her what we knew of Sinclair's generator. Maybe Valpredo was looking at me disapprovingly, maybe not.

"We know that the field can damage a human arm in a few seconds. What we want to know," I said, "is whether the killer is now wandering around with a half-decayed hand or arm -- or foot, for that -- "

She stood and pulled the upper half of her body stocking down around her waist.

She looked very much a real woman. If I hadn't known -- and why would it matter? These days the sex change operation is elaborate and perfect. Hell with it; I was on duty. Valpredo was looking nonchalant, waiting for me.

I examined both of her arms with my eyes and my three hands. There was nothing. Not even a bruise.

"My legs, too?"

I said, "Not if you can stand on them."

Next question. Could an artificial arm operate within the field?

"Larry? You mean _Larry_? You're out of your teeny mind."

"Take it as a hypothetical question."

She shrugged. "Your guess is as good as mine. There aren't any experts on inertialess fields."

"There was one. He's dead," I reminded her.

"All I know is what I learned watching the Gray Lensman show in the holo wall when I was a kid." She smiled suddenly. "That old space opera."

Valpredo laughed. "You, too? I used to watch that show in study hall on a little pocket phone. One day the principal caught me at it."

"Sure. And then we outgrew it. Too bad. Those inertialess ships ... I'm sure an inertialess ship wouldn't behave like those did. You couldn't possibly get rid of the time compression effect." She took a long pull on her drink, set it down, and said, "Yes and no. He could reach in,

but -- you see the problem? The nerve impulses that move the motors in Larry's arm, they're coming into the field too slowly."

"Sure."

"But if Larry closed his fist on something, say, and reached into the field with it, it would probably stay closed. He could have brained Ray with -- no, he couldn't. The poker wouldn't be moving any faster than a glacier. Ray would just dodge."

And he couldn't pull a poker out of the field, either. His fist wouldn't close on it after it was inside. But he could have tried and still left with his arm intact, I thought.

Did Urthiel know anything of the circumstances surrounding Edward Sinclair's exemption?

"Oh, that's an old story," she said. "Sure, I heard about it. How could it possibly have anything to do with, with Ray's murder?"

"I don't know," I confessed. "I'm just thrashing around."

"Well, you'll probably get it more accurately from the UN files. Edward Sinclair did some mathematics on the fields that scoop up interstellar hydrogen for the cargo ramrobots. He was a shoo-in for the exemption. That's the surest way of getting it: make a breakthrough in anything that has anything to do with the interstellar colonies. Every time you move one man away from Earth, the population drops by one."

"What was wrong with it?"

"Nothing anyone could prove. Remember, the Fertility Restriction Laws were new then. They couldn't stand a real test. But Edward Sinclair's a pure math man. He works with number theory, not practical applications. I've seen Edward's equations, and they're closer to something Ray would come up with. And Ray didn't need the exemption. He never wanted children."

"So you think -- "

"I don't _care_ which of them redesigned the ramscoops. Diddling the Fertility Board like that, that takes _brains_." She swallowed the rest of her drink, set the glass down. "Breeding for brains is never a mistake. It's no challenge to the Fertility Board, either. The people who do the damage are the ones who go into hiding when their shots come due, have their babies, then scream to high heaven when the board has to sterilize them. Too many of those and we won't have Fertility Laws anymore. And _that_ -- " She didn't have to finish.

Had Sinclair known that Pauline Urthiel was once Paul?

She stared. "Now just what the bleep has that got to do with anything?"

I'd been toying with the idea that Sinclair might have been blackmailing Urthiel with that information. Not for money but for credit in some discovery they'd made together. "Just thrashing around," I said.

"Well ... all right. I don't know if Ray knew or not. He never raised the subject, but he never made a pass, either, and he must have researched me before he hired me. And, say, listen: Larry doesn't know. I'd appreciate it if you wouldn't blurt it out."

"Okay."

"See, he had his children by his first wife. I'm not denying him children ... Maybe he married me because I had a touch of, um, masculine insight. Maybe. But he doesn't know it, and he doesn't want to. I don't know whether he'd laugh it off or kill me."

* * * *

I had Valpredo drop me off at ARM Headquarters.

_This peculiar machine really does bother me, Gil_ ... Well it should, Julio. The Los Angeles Police were not trained to deal with a mad scientist's nightmare running quietly in the middle of a murder scene.

Granted that Janice wasn't the type. Not for this murder. But Drew Porter was precisely the type to evolve a perfect murder around Sinclair's generator, purely as an intellectual exercise. He might have guided her through it; he might even have been there and used the elevator before she shut it off. It was the one thing he forgot to tell her: not to shut off the elevator.

Or: he outlined a perfect murder to her, purely as a puzzle, never dreaming she'd go through with it -- badly.

Or: one of them killed Janice's uncle on impulse. No telling what he'd said that one of them couldn't tolerate. But the machine had been right there in the living room, and Drew had wrapped his big arm around Janice and said, _Wait, don't do anything yet; let's think this out_...

Take any of these as the true state of affairs, and a prosecutor could have a hell of a time proving it. He could show that no killer could possibly have left the scene of the crime without Janice Sinclair's help, and therefore ... But what about that glowing thing, that time machine built by the dead man? _Could_ it have freed a killer from an effectively locked room? How could a judge know its power?

Well, could it?

Bera might know.

The machine was running. I caught the faint violet glow as I stepped into the laboratory and a flickering next to it ... and then it was off, and Jackson Bera stood suddenly beside it, grinning, silent, waiting.

I wasn't about to spoil his fun. I said, "Well? Is it an interstellar drive?"

"Yes!"

A warm glow spread through me. I said, "Okay."

"It's a low-inertia field," said Bera. "Things inside lose most of their inertia ... not their mass, just the resistance to movement. Ratio of about five hundred to one. The interface is sharp as a razor. We think there are quantum levels involved."

"Uh huh. The field doesn't affect time directly?"

"No, it ... I shouldn't say that. Who the hell knows what time really is? It affects chemical and nuclear reactions, energy release of all kinds ... but it doesn't affect the speed of light. You know, it's kind of kicky to be measuring the speed of light at 370 miles per second with honest instruments."

Dammit. I'd been half hoping it was an FTL drive. I said, "Did you ever find out what was causing that blue glow?"

Bera laughed at me. "Watch." He'd rigged a remote switch to turn the machine on. He used it, then struck a match and flipped it toward the blue glow. As it crossed an invisible barrier, the match flared violet-white for something less than an eye blink. I blinked. It had been like a flashbulb going off.

I said, "Oh, _sure_. The machinery's warm."

"Right. The blue glow is just infrared radiation being boosted to violet when it enters normal time."

Bera shouldn't have had to tell me that. Embarrassed, I changed the subject. "But you said it was an interstellar drive."

"Yah. It's got drawbacks," Bera said. "We can't just put a field around a whole starship. The crew would think they'd lowered the speed of light, but so what? A slowboat doesn't get that close to lightspeed anyway. They'd save a little trip time, but they'd have to live through it five hundred times as fast."

"How about if you just put the field around your fuel tanks?"

Bera nodded. "That's what they'll probably do. Leave the motor and the life support system outside. You could carry a god-awful amount of fuel that way ... Well, it's not our department. Someone else'll be designing the starships," he said a bit wistfully.

"Have you thought of this thing in relation to robbing banks? Or espionage?"

"If a gang could afford to build one of these jobs, they wouldn't need to rob banks." He ruminated. "I hate making anything this big a UN secret. But I guess you're right. The average government could afford a whole stable of the things."

"Thus combining James Bond and the Flash."

He rapped on the plastic frame. "Want to try it?"

"Sure," I said.

_Heart to brain: THUD! What're you doing? You'll get us all killed! I knew we should never have put you in charge of things_ ... I stepped up to the generator, waited for Bera to scamper beyond range, then pulled the switch.

Everything turned deep red. Bera became a statue.

Well, here I was. The second hand on the wall clock had stopped moving. I took two steps forward and rapped with my knuckles. Rapped, hell: it was like rapping on contact cement. The invisible wall was tacky.

I tried leaning on it for a minute or so. That worked fine until I tried to pull away, and then I knew I'd done something stupid. I was embedded in the interface. It took me another minute to pull loose, and then I went sprawling backward; I'd picked up too much inward velocity, and it all came into the field with me.

At that, I'd been lucky. If I'd leaned there a little longer, I'd have lost my leverage. I'd have been sinking deeper and deeper into the interface, unable to yell to Bera, building up more and more velocity outside the field.

I picked myself up and tried something safer. I took out my pen and dropped it. It fell normally: thirty-two feet per second per second, field time. Which scratched one theory as to how the killer had thought he would be leaving.

I switched the machine off. "Something I'd like to try," I told Bera. "Can you hang the machine in the air, say by a cable around the frame?"

"What have you got in mind?"

"I want to try standing on the bottom of the field."

Bera looked dubious.

It took us twenty minutes to set it up. Bera took no chances. He lifted the generator about five feet. Since the field seemed to center on that oddly shaped piece of silver, that put the bottom of the field just a foot in the air. We moved a stepladder into range, and I stood on the stepladder and turned on the generator.

I stepped off.

Walking down the side of the field was like walking in progressively stickier taffy. When I stood on the bottom, I could just reach the switch.

My shoes were stuck solid. I could pull my feet out of them, but there was no place to stand except in my own shoes. A minute later my feet were stuck, too: I could pull one loose, but only by fixing the other ever more deeply in the interface. I sank deeper, and all sensation left the soles of my feet. It was scary, though I knew nothing terrible could happen to me. My feet wouldn't die out there; they wouldn't have time.

But the interface was up to my ankles now, and I started to wonder what kind of velocity they were building up out there. I pushed the switch up. The lights flashed bright, and my feet slapped the floor hard.

Bera said, "Well? Learn anything?"

"Yah. I don't want to try a real test: I might wreck the machine."

"What kind of real test -- ?"

"Dropping it forty stories with the field on. Quit worrying; I'm not going to do it."

"Right. You aren't."

"You know, this time compression effect would work for more than just spacecraft. After you're on the colony world, you could raise full-grown cattle from frozen fertilized eggs in just a few minutes."

"Mmm ... Yah." The happy smile flashing white against darkness, the infinity look in Bera's eyes ... Bera liked playing with ideas. "Think of one of these mounted on a truck, say on Jinx. You could explore the shoreline regions without ever worrying about the Bandersnatchi attacking. They'd never move fast enough. You could drive across any alien world and catch the whole ecology laid out around you, none of it running from the truck. Predators in midleap, birds in midflight, couples in courtship."

"Or larger groups."

"I ... think that habit is unique to humans." He looked at me sideways. "You wouldn't spy on _people_, would you? Or shouldn't I ask?"

"That five-hundred-to-one ratio. Is that constant?"

He came back to here and now. "We don't know. Our theory hasn't caught up to the hardware it's supposed to fit. I wish to hell we had Sinclair's notes."

"You were supposed to send a programmer out there."

"He came back," Bera said viciously. "Clayton Wolfe. Clay says the tapes in Sinclair's computer were all wiped before he got there. I don't know whether to believe him or not. Sinclair was a secretive bastard, wasn't he?"

"Yah. One false move on Clay's part and the computer might have wiped everything. But he says different?"

"He says the computer was blank, a newborn mind all ready to be taught. Gil, is that possible? Could whoever have killed Sinclair have wiped the tapes?"

"Sure, why not? What he couldn't have done is left afterward." I told him a little about the problem. "It's even worse than that, because as Ordaz keeps pointing out, he thought he'd be leaving with the machine. I thought he might have been planning to roll the generator off the roof, step off with it, and float down. But that wouldn't work. Not if it falls five hundred times as fast. He'd have been killed."

"Losing the machine maybe saved his life."

"But _how did he get out_?"

Bera laughed at my frustration. "Couldn't his niece be the one?"

"Sure, she could have killed her uncle for the money. But I can't see how she'd have a motive to wipe the computer. Unless -- "

"Something?"

"Maybe. Never mind." Did Bera ever miss this kind of manhunting? But I wasn't ready to discuss this yet; I didn't know enough. "Tell me more about the machine. Can you vary that five-hundred-to-one ratio?"

He shrugged. "We tried adding more batteries. We thought it might boost the field strength. We were wrong; it just expanded the boundary a little. And using one less battery turns it off completely. So the ratio seems to be constant, and there do seem to be quantum levels involved. We'll know better when we build another machine."

"How so?"

"Well, there are all kinds of good questions," Bera said. "What happens when the fields of two generators intersect? They might just add, but maybe not. That quantum effect ... And what happens if the generators are right next to each other, operating in each other's accelerated time? The speed of light could drop to a few feet per second. Throw a punch and your hand gets shorter!"

"That'd be kicky, all right."

"Dangerous, too. Man, we'd better try that one on the moon!"

"I don't see that."

"Look, with one machine going, infrared light comes out violet. If two machines were boosting each other's performance, what kind of radiation would they put out? Anything from X rays to antimatter particles."

"An expensive way to build a bomb."

"Well, but it's a bomb you can use over and over again."

I laughed. "We did find you an expert," I said. "You may not need Sinclair's tapes. Bernath Peterfi says he was working with Sinclair. He could be lying -- more likely he was working _for_ him, under contract -- but at least he knows what the machine does."

Bera seemed relieved at that. He took down Peterfi's address. I left him there in the laboratory, playing with his new toy.

* * * *

The file from the city morgue was sitting on my desk, open, waiting for me since this morning. Two dead ones looked up at me through sockets of blackened bone, but not accusingly. They had patience. They could wait.

The computer had processed my search pattern. I braced myself with a cup of coffee, then started leafing through the thick stack of printout. When I knew what had burned away two human faces, I'd be close to knowing who. Find the tool, find the killer. And the tool must be unique or close to it.

Lasers, lasers -- more than half the machine's suggestions seemed to be lasers. Incredible the way lasers seemed to breed and mutate throughout human industry. Laser radar. The laser guidance system on a tunneling machine. Some suggestions were obviously unworkable, and one was a lot too workable.

A standard hunting laser fires in pulses. But it can be jiggered for a much longer pulse or even a continuous burst.

Set a hunting laser for a long pulse and put a grid over the lens. The mesh has to be optically fine, on the order of angstroms. Now the beam will spread as it leaves the grid. A second of pulse will vaporize the grid, leaving no evidence. The grid would be no bigger than a contact lens; if you didn't trust your aim, you could carry a pocketful of them.

The grid-equipped laser would be less efficient, as a rifle with a silencer is less efficient. But the grid would make the murder weapon impossible to identify.

I thought about it and got cold chills. Assassination is already a recognized branch of politics. If this got out -- But that was the trouble; someone seemed to have thought of it already. If not, someone would. Someone always did.

I wrote up a memo for Lucas Garner. I couldn't think of anyone better qualified to deal with this kind of sociological problem.

Nothing else in the stack of printout caught my eye. Later I'd have to go through it in detail. For now I pushed it aside and punched for messages.

Bates, the coroner, had finished the autopsies on the two charred corpses. Nothing new. But records had identified the fingerprints. Two missing persons, disappeared six and eight months ago. Ah ha!

I knew that pattern. I didn't even look at the names; I just skipped on to the gene coding.

Right. The fingerprints did not match the genes. All twenty fingertips must be transplants. And the man's scalp was a transplant; his own hair had been blond.

I leaned back in my chair, gazing fondly down at holograms of charred skulls.

You evil sons of bitches. Organleggers, both of you. With all that raw material available, most organleggers change their fingerprints constantly -- and their retina prints -- but we'd never get prints from those charred eyeballs. So, weird weapon or no, they were ARM business. My business.

And we still didn't know what had killed them, or who.

It could hardly have been a rival gang. For one thing, there was no competition. There must be plenty of business for every organlegger left alive after the ARM swept through them last year. For another, why had they been dumped on a city slidewalk? Rival organleggers would have taken them apart for their own organ banks. Waste not, want not.

On that same philosophy, I had something to be deeply involved in when the mother hunt broke. Sinclair's death wasn't ARM business, and his time compression field wasn't in my field. This was both.

I wondered what end of the business the dead ones had been in. The file gave their estimated ages: forty for the man, forty-three for the woman, give or take three years each. Too old to be raiding the city street for donors. That takes youth and muscle. I billed them as doctors, culturing the transplants and doing the operations, or salespersons, charged with quietly letting prospective clients know where they could get an operation without waiting two years for the public organ banks to come up with material.

So they'd tried to sell someone a new kidney and had been killed for their impudence. That would make the killer a hero.

So why hide them for three days, then drag them out onto a city slidewalk in the dead of night?

Because they'd been killed with a fearsome new weapon?

I looked at the burned faces and thought: fearsome, right. Whatever did that _had_ to be strictly a murder weapon. As the optical grid over a laser lens would be strictly a murder technique.

So a secretive scientist and his deformed assistant, fearful of rousing the wrath of the villagers, had dithered over the bodies for three days, then disposed of them in that clumsy fashion because they panicked when the bodies started to smell. Maybe.

But a prospective client needn't have used his shiny new terror weapon. He had only to call the cops after they were gone. It read better if the killer was a prospective _donor_; he'd fight with anything he could get his hands on.

I flipped back to full shots of the bodies. They looked to be in good condition. Not much flab. You don't collect a donor by putting an armlock on him; you use a needle gun. But you still need muscle to pick up the body and move it to your car, and you have to do that damn quick. Hmmm...

Someone knocked at my door.

I shouted, "Come on in!"

Drew Porter came in. He was big enough to fill the office, and he moved with a grace he must have learned on a board. "Mr. Hamilton? I'd like to talk to you."

"Sure. What about?"

He didn't seem to know what to do with his hands. He looked grimly determined. "You're an ARM," he said. "You're not actually investigating Uncle Ray's murder. That's right, isn't it?"

"That's right. Our concern is with the generator. Coffee?"

"Yes, thanks. But you know all about the killing. I thought I'd like to talk to you, straighten out some of my own ideas."

"Go ahead." I punched for two coffees.

"Ordaz thinks Janice did it, doesn't he?"

"Probably. I'm not good at reading Ordaz's mind. But it seems to narrow down to two distinct groups of possible killers: Janice and everyone else. Here's your coffee."

"Janice didn't do it." He took the cup from me, gulped at it, set it down on my desk, and forgot about it.

"Janice and X," I said. "But X couldn't have left. In fact, X couldn't have left even if he'd had the machine he came for. And we still don't know why he didn't just take the elevator."

He scowled as he thought that through. "Say he had a way to leave," he said. "He wanted to take the machine -- he _had_ to want that, because he tried to use the machine to set up an alibi. But even if he couldn't take the machine he'd still use his alternative way out."

"Why?"

"It'd leave Janice holding the bag if he knew Janice coming home. If he didn't know that, he'd be leaving the police with a locked room."

"Locked room mysteries are good clean fun, but I never heard of one happening in real life. In fiction they usually happen by accident." I waved aside his protest. "Never mind. How did he get out?"

Porter didn't answer.

"Would you care to look at the case against Janice Sinclair?"

"She's the only one who could have done it," he said bitterly. "But she didn't. She couldn't kill anyone, not in that cold-blooded, prepackaged way, with an alibi all set up and a weird machine at the heart of it. Look, that machine is too _complicated_ for Janice."

"No, she isn't the type. But -- no offense intended -- you are."

He grinned at that. "Me? Well, maybe I am. But why would I want to?"

"You're in love with her. I think you'd do anything for her. Aside from that, you might enjoy setting up a perfect murder. And there's the money."

"You've got a funny idea of a perfect murder."

"Say I was being tactful."

He laughed at that. "All right. Say I set up a murder for the love of Janice. Damn it, if she had that much hate in her, I wouldn't love her! Why would she want to kill Uncle Ray?"

I dithered about whether to drop that on him. Decided yes. "Do you know anything about Edward Sinclair's exemption?"

"Yah. Janice told me something about..." He trailed off.

"Just what did she tell you?"

"I don't have to say."

That was probably intelligent. "All right," I said. "For the sake of argument, let's assume it was Raymond Sinclair who worked out the math for the new ramrobot scoops, and Edward took the credit, with Raymond's connivance. It was probably Raymond's idea. How would that sit with Edward?"

"I'd think he'd be grateful forever," Porter said. "Janice says he is."

"Maybe. But people are funny, aren't they? Being grateful for fifty years could get on a man's nerves. It's not a natural emotion."

"You're so young to be so cynical," Porter said pityingly.

"I'm trying to think this out like a prosecution lawyer. If these brothers saw each other too often, Edward might get to feeling embarrassed around Raymond. He'd have a hard time relaxing with him. The rumors wouldn't help ... Oh, yes, there are rumors. I've been told that Edward couldn't have worked out those equations because he doesn't have the ability. If that kind of thing got back to Edward, how would he like it? He might even start avoiding his brother. Then Ray might remind brother Edward of just how much he owed him ... and that's the kiss of death."

"Janice says no."

"Janice could have picked up the hate from her father. Or she might have started worrying about what would happen if Uncle Ray changed his mind one day. It could happen any time if things were getting strained between the elder Sinclairs. So one day she shut his mouth -- "

Porter growled in his throat.

"I'm just trying to show you what you're up against. One more thing: the killer may have wiped the tapes in Sinclair's computer."

"Oh?" Porter thought that over. "Yah. Janice could have done that just in case there were some notes in there, notes on Ed Sinclair's ramscoop field equations. But look: X could have wiped those tapes, too. Stealing the generator doesn't do him any good unless he wipes it out of Uncle Ray's computer."

"Shall we get back to the case against X?"

"With pleasure." He dropped into a chair. Watching his face smooth out, I added, _and with great relief_.

I said, "Let's not call him X. Call him K for killer." We already had an Ecks involved ... and his family name probably _had_ been X once upon a time. "We've been assuming K set up Sinclair's time compression effect as an alibi."

Porter smiled. "It's a lovely idea. _Elegant_, as a mathematician would say. Remember, I never saw the actual murder scene. Just chalk marks."

"It was -- macabre. Like a piece of surrealism. A very bloody practical joke. K could have deliberately set it up that way if his mind is twisted enough."

"If he's that twisted, he probably escaped by running himself down the garbage disposal."

"Pauline Urthiel thought he might be a psychotic. Someone who worked with Sinclair who thought he wasn't getting enough credit." Like Peterfi, I thought, or Pauline herself.

"I like the alibi theory."

"It bothers me. Too many people knew about the machine. How did he expect to get away with it? Lawrence Ecks knew about it. Peterfi knew about it. Peterfi knew enough about the machine to rebuild it from scratch. Or so he says. You and Janice saw it in action."

"Say he's crazy, then. Say he hated Uncle Ray enough to kill him and then set him up in a makeshift Dali painting. He'd still have to get _out_." Porter was working his hands together. The muscles bulged and rippled in his arms. "If the elevator hadn't been locked and on Uncle Ray's floor, there wouldn't be a problem."

"So?"

"So. Janice came home, called the elevator up, and locked it. She does that without thinking. She had a bad shock last night. This morning she didn't remember."

"And this evening it could come back to her."

Porter looked up sharply. "I wouldn't -- "

"You'd better think long and hard before you do. If Ordaz is sixty percent sure of her now, he'll be a hundred percent sure when she lays that on him."

Porter was working his muscles again. In a low voice he said, "It's possible, isn't it?"

"Sure. It makes things a lot simpler, too. But if Janice said it now, she'd sound like a liar."

"But it's _possible_."

"I give up. Sure, it's possible."

"Then who's our killer?"

There wasn't any reason I shouldn't consider the question. It wasn't my case at all. I did, and presently I laughed. "Did I say it'd make things simpler? Man, it throws the case _wide open_! _Anyone_ could have done it. Uh, anyone but Steeves. Steeves wouldn't have had any reason to come back this morning."

Porter looked glum. "Steeves wouldn't have done it anyway."

"He was your suggestion."

"Oh, in pure mechanical terms, he's the only one who didn't need a way out. But you don't know Steeves. He's a big, brawny guy with a beer belly and no brains. A nice guy, you understand, I _like_ him, but if he ever killed anyone, it'd be with a beer bottle. And he was proud of Uncle Ray. He liked having Raymond Sinclair in his building."

"Okay, forget Steeves. Is there anyone you'd particularly like to pin it on? Bearing in mind that now _anyone_ could get in to do it."

"Not anyone. Anyone in the elevator computer, plus anyone Uncle Ray might have let up."

"Well?"

He shook his head.

"You make a hell of an amateur detective. You're afraid to accuse anyone."

He shrugged, smiling, embarrassed.

"What about Peterfi? Now that Sinclair's dead, he can claim they were equal partners in the, uh, time machine. And he tumbled to it awfully fast. The moment Valpredo told him Sinclair was dead, Peterfi was his partner."

"Sounds typical."

"Could he be telling the truth?"

"I'd say he's lying. Doesn't make him a killer, though."

"No. What about Ecks? If he didn't know Peterfi was involved, he might have tried the same thing. Does he need money?"

"Not hardly. And he's been with Uncle Ray for longer than I've been alive."

"Maybe he was after the exemption. He's had kids, but not by his present wife. He may not know she can't have children."

"Pauline _likes_ children. I've seen her with them." Porter looked at me curiously. "I don't see having children as that big a motive."

"You're young. Then there's Pauline herself. Sinclair knew something about her. Or Sinclair might have told Ecks, and Ecks blew up and killed him for it."

Porter shook his head. "In red rage? I can't think of anything that'd make Larry do that. Pauline, maybe. Larry, no."

But, I thought, there are men who would kill if they learned that their wives had gone through a sex change. I said, "Whoever killed Sinclair, if he wasn't crazy, he had to want to take the machine. One way might have been to lower it by rope..." I trailed off. Fifty pounds or so, lowered two stories by nylon line. Ecks's steel and plastic arm ... or the muscles now rolling like boulders in Porter's arms. I thought Porter could have managed it.

Or maybe he'd thought he could. He hadn't actually had to go through with it.

My phone rang.

It was Ordaz. "Have you made any progress on the time machine? I'm told that Dr. Sinclair's computer -- "

"Was wiped, yah. But that's all right. We're learning quite a lot about it. If we run into trouble, Bernath Peterfi can help us. He helped build it. Where are you now?"

"At Dr. Sinclair's apartment. We had some further questions for Janice Sinclair."

Porter twitched. I said, "All right, we'll be right over. Andrew Porter's with me." I hung up and turned to Porter. "Does Janice know she's a suspect?"

"No. Please don't tell her unless you have to. I'm not sure she could take it."

* * * *

I had the taxi drop us at the lobby level of the Rodewald Building. When I told Porter I wanted a ride in the elevator, he just nodded.

The elevator to Raymond Sinclair's penthouse was a box with a seat in it. It would have been comfortable for one, cozy for two good friends. With me and Porter in it, it was crowded. Porter hunched his knees and tried to fold into himself. He seemed used to it

He probably was. Most apartment elevators are like that. Why waste room on an elevator shaft when the same space can go into apartments?

It was a fast ride. The seat was necessary; it was two gees going up and a longer period at half a gee slowing down while lighted numbers flickered past. Numbers but no doors.

"Hey, Porter. If this elevator jammed, would there be a door to let us out?"

He gave me a funny look and said he didn't know. "Why worry about it? If it jammed at this speed, it'd come apart like a handful of shredded lettuce."

It was just claustrophobic enough to make me wonder. K hadn't left by elevator. Why not? Because the ride up had terrified him? _Brain to memory: dig into the medical records of that list of suspects. Claustrophobia._ Too bad the elevator brain didn't keep records. We could find out which of them had used the boxlike elevator once or not at all.

In which case we'd be looking for K2. By now I was thinking in terms of three groups. K1 killed Sinclair, then tried to use the low-inertia field as both loot and alibi. K2 was crazy; he hadn't wanted the generator at all, except as a way to set up his macabre tableau. K3 was Janice and Drew Porter.

Janice was there when the doors slid open. She was wan, and her shoulders slumped. But when she saw Porter, she smiled like sunlight and ran to him. Her run was wobbly, thrown off by the missing weight of her arm.

The wide brown circle was still there in the grass, marked with white chalk and the yellow chemical that picks up bloodstains. White outlines to mark the vanished body, the generator, the poker.

Something knocked at the back door of my mind. I looked from the chalk outlines, to the open elevator, to the chalk ... and a third of the puzzle fell into place.

So simple. We were looking for K1 ... and I had a pretty good idea who he was.

Ordaz was asking me, "How did you happen to arrive with Mr. Porter?"

"He came to my office. We were talking about a hypothetical killer -- " I lowered my voice slightly. " -- a killer who isn't Janice."

"Very good. Did you reason out how he must have left?"

"Not yet. But play the game with me. Say there was a way."

Porter and Janice joined us, their arms about each other's waists. Ordaz said, "Very well. We assume there was a way out. Did he improvise it? And why did he not use the elevator?"

"He must have had it in mind when he got here. He didn't use the elevator because he was planning to take the machine. It wouldn't have fit."

They all stared at the chalk outline of the generator. So simple. Porter said, "Yah! Then he used it anyway and left you a locked room mystery!"

"That may have been his mistake," Ordaz said grimly. "When we know his escape route, we may find that only one man could have used it. But of course we do not even know that the route exists."

I changed the subject. "Have you got everyone on the elevator tape identified?"

Valpredo dug out his spiral notebook and flipped to the jotted names of the people permitted to use Sinclair's elevator. He showed it to Porter. "Have you seen this?"

Porter studied it. "No, but I can guess what it is. Let's see ... Hans Drucker was Janice's lover before I came along. We still see him. In fact, he was at that beach party last night at the Randalls'."

"He flopped on the Randalls' rug last night," Valpredo said. "Him and four others. One of the better alibis."

"Oh, _Hans_ wouldn't have anything to do with this!" Janice exclaimed. The idea horrified her.

Porter was still looking at the list. "You know about most of these people already. Bertha Hall and Muriel Sandusky were lady friends of Uncle Ray's. Bertha goes backpacking with him."

"We interviewed them, too," Valpredo told me. "You can hear the tapes if you like."

"No, just give me the gist. I already know who the killer is."

Ordaz raised his eyebrows at that, and Janice said, "Oh, good! Who?" which question I answered with a secretive smile. Nobody actually called me a liar.

Valpredo said, "Muriel Sandusky's been living in England for almost a year. Married. Hasn't seen Sinclair in years. Big, beautiful redhead."

"She had a crush on Uncle Ray once," Janice said. "And vice versa. I think his lasted longer."

"Bertha Hall is something else again," Valpredo continued. "Sinclair's age and in good shape. Wiry. She says that when Sinclair was on the home stretch on a project, he gave up everything: friends, social life, exercise. Afterward he'd call Bertha and go backpacking with her to catch up with himself. He called her two nights ago and set a date for next Monday."

I said, "Alibi?"

"Nope."

"Really!" Janice said indignantly. "Why, we've known Bertha since I was that high! If you know who killed Uncle Ray, why don't you just say so?"

"Out of this list, I sure do, given certain assumptions. But I don't know how he got out, or how he expected to, or whether we can prove it on him. I can't accuse anyone _now_. It's a damn shame he didn't lose his arm reaching for that poker."

Porter looked frustrated. So did Janice.

"You would not want to face a lawsuit," Ordaz suggested delicately. "What of Sinclair's machine?"

"It's an inertialess drive, sort of. Lower the inertia, time speeds up. Bera's already learned a lot about it, but it'll be a while before he can really..."

"You were saying?" Ordaz asked when I trailed off.

"Sinclair was _finished_ with the damn thing."

"Sure he was," Porter said. "He wouldn't have been showing it around otherwise."

"Or calling Bertha for a backpacking expedition. Or spreading rumors about what he had. Yeah. Sure, he knew everything he could learn about that machine. Julio, you were cheated. It all depends on the machine. And the bastard did wrack up his arm, and we can prove it on him."

We piled into Ordaz's commandeered taxi: me and Ordaz and Valpredo and Porter. Valpredo set the thing for conventional speeds so he wouldn't have to worry about driving. We'd turned the interior chairs to face each other.

"This is the part I won't guarantee," I said, sketching rapidly in Valpredo's borrowed notebook. "But remember, he had a length of line with him. He must have expected to use it. Here's how he planned to get out."

I sketched in a box to represent Sinclair's generator, a stick figure clinging to the frame. A circle around them to represent the field. A bowknot tied to the machine, with one end trailing up through the field.

"See it? He goes up the stairs with the field on. The camera has about one chance in eight of catching him while he's moving at that speed. He wheels the machine to the edge of the roof, ties the line to it, throws the line a good distance away, pushes the generator off the roof, and steps off with it. The line falls at thirty-two feet per second squared, normal time, plus a little more because the machine and the killer are tugging down on it. Not hard, because they're in a low-inertia field. By the time the killer reaches ground, he's moving at something more than, uh, twelve hundred feet per second over five hundred ... uh, say three feet per second internal time, and he's got to pull the machine out of the way fast, because the rope is going to hit like a bomb."

"It looks like it would work," Porter said.

"Yah. I thought for a while that he could just stand on the bottom of the field. A little fooling with the machine cured me of that. He'd smash both legs. But he could hang on to the frame; it's strong enough."

"But he didn't have the machine," Valpredo pointed out.

"That's where you got cheated. What happens when two fields intersect?"

They looked blank.

"It's not a trivial question. Nobody knows the answer yet. _But Sinclair did._ He had to; he was _finished_. He must have had two machines. The killer took the second machine."

Ordaz said, "Ahh."

Porter said, "Who's K?"

We were settling on the carport. Valpredo knew where we were, but he didn't say anything. We left the taxi and headed for the elevators.

"That's a lot easier," I said. "He expected to use the machine as an alibi. That's silly, considering how many people knew it existed. But if he didn't know that Sinclair was ready to start showing it to people -- specifically to you and Janice -- who's left? Ecks only knew it was some kind interstellar drive."

The elevator was uncommonly large. We piled into it.

"And," Valpredo said, "there's the matter of the arm. I think I've got that figured, too."

"I gave you enough clues," I told him.

* * * *

Peterfi was a long time answering our buzz. He may have studied us through the door camera, wondering why a parade was marching through his hallway. Then he spoke through the grid. "Yes? What is it?"

"Police. Open up," Valpredo said.

"Do you have a warrant?"

I stepped forward and showed my ident to the camera. "I'm an ARM. I don't need a warrant. Open up. We won't keep you long." _One way or another._

He opened the door. He looked neater now than he had this afternoon despite informal brown indoor pajamas. "Just you," he said. He let me in, then started to close the door on the others.

Valpredo put his hand against the door. "Hey -- "

"It's okay," I said. Peterfi was smaller than I was, and I had a needle gun. Valpredo shrugged and let him close the door.

My mistake. I had two-thirds of the puzzle, and I thought I had it all.

Peterfi folded his arms and said, "Well? What is it you want to search this time? Would you like to examine my legs?"

"No, let's start with the insulin feeder on your upper arm."

"Certainly," he said, and startled the hell out of me.

I waited while he took off his shirt -- unnecessary, but he needn't know that -- then ran my imaginary fingers through the insulin feed. The reserve was nearly full. "I should have known," I said. "Dammit. You got six months worth of insulin from the organlegger."

His eyebrows went up. "Organlegger?" He pulled loose. "Is this an accusation, Mr. Hamilton? I'm taping this for my attorney."

And I was setting myself up for a lawsuit. The hell with it. "Yah, it's an accusation. You killed Sinclair. Nobody else could have tried that alibi stunt."

He looked puzzled -- honestly, I thought. "Why not?"

"If anyone else had tried to set up an alibi with Sinclair's generator, Peterfi, you would have told the police all about what it was and how it worked. But you were the only one who knew that until last night, when he started showing it around."

There was only one thing he could say to that kind of logic, and he said it. "Still recording, Mr. Hamilton."

"Record and be damned. There are other things we can check. Your grocery delivery service. Your water bill."

He didn't flinch. He was smiling. Was it a bluff? I sniffed the air. Six months worth of body odor emitted in one night? By a man who hadn't taken more than four or five baths in six months? But his air-conditioning was too good.

The curtains were open now to the night and the ocean. They'd been closed this afternoon, and he'd been squinting. But it wasn't evidence. The lights: he only had one light burning now, and so what?

The big, powerful campout flashlight sitting on a small table against a wall. I hadn't even noticed it this afternoon. Now I was sure I knew what he'd used it for, but how to prove it?

Groceries ... "If you didn't buy six months worth of groceries last night, you must have stolen them. Sinclair's generator is perfect for thefts. We'll check the local supermarkets."

"And link the thefts to me? How?"

He was too bright to have kept the generator. But come to think of it, where could he abandon it? He was _guilty_. He couldn't have covered _all_ his tracks --

"Peterfi? I've got it."

He believed me. I saw it in the way he braced himself. Maybe he'd worked it out before I did. I said, "Your contraceptive shots must have worn off six months early. Your organlegger couldn't get you that; he's got no reason to keep contraceptives around. You're dead, Peterfi."

"I might as well be. Damn you, Hamilton! You've cost me the exemption!"

"They won't try you right away. We can't afford to lose what's in your head. You know too much about Sinclair's generator."

"Our generator! We built it together!"

"Yah."

"You won't try me at all," he said more calmly. "Are you going to tell a court how the killer left Ray's apartment?"

I dug out my sketch and handed it to him. While he was studying it, I said, "How did you like going off the roof? You couldn't have _known_ it would work."

He looked up. His words came slowly, reluctantly. I guess he had to tell someone, and it didn't matter now. "By then I didn't care. My arm hung like a dead rabbit, and it stank. It took me three minutes to reach the ground. I thought I'd die on the way."

"Where'd you dig up an organlegger that fast?"

His eyes called me a fool. "Can't you guess? Three years ago. I was hoping diabetes could be cured by a transplant. When the government hospitals couldn't help me, I went to an organlegger. I was lucky he was still in business last night."

He drooped. It seemed that all the anger went out of him. "Then it was six months in the field, waiting for the scars to heal. In the dark. I tried taking that big campout flashlight in with me." He laughed bitterly. "I gave that up after I noticed the walls were smoldering."

The wall above that little table had a scorched look. I should have wondered about that earlier.

"No baths," he was saying. "I was afraid to use up that much water. No exercise, practically. But I had to eat, didn't I? And all for nothing."

"Will you tell us how to find the organlegger you dealt with?"

"This is your big day, isn't it, Hamilton? All right, why not? It won't do you any good."

"Why not?"

He looked up at me very strangely.

Then he spun about and ran.

He caught me flat-footed. I jumped after him. I didn't know what he had in mind; there was only one exit to the apartment, excluding the balcony, and he wasn't headed there. He seemed to be trying to reach a blank wall with a small table set against it and a camp flashlight on it and a drawer in it. I saw the drawer and thought, _Gun!_ And I surged after him and got him by the wrist just as he reached the wall switch above the table.

I threw my weight backward and yanked him away from there ... and then the field came on.

I held a hand and arm up to the elbow. Beyond was a fluttering of violet light: Peterfi was thrashing frantically in a low-inertia field. I hung on while I tried to figure out what was happening.

The second generator was here somewhere. In the wall? The switch seemed to have been recently plastered in, now that I saw it close. Figure a closet on the other side and the generator in it. Peterfi must have drilled through the wall and fixed that switch. Sure, what else did he have to do with six months of spare time?

No point in yelling for help. Peterfi's soundproofing was too modern. And if I didn't let go, Peterfi would die of thirst in a few minutes.

Peterfi's feet came straight at my jaw. I threw myself down, and the edge of a boot sole nearly tore my ear off. I rolled forward in time to grab his ankle. There was more violet fluttering, and his other leg thrashed wildly outside the field. Too many conflicting nerve impulses were pouring into the muscles. The leg flopped about like something dying. If I didn't let go, he'd break it in a dozen places.

He'd knocked the table over. I didn't see it fall, but suddenly it was lying on its side. The top, drawer included, must have been well beyond the field. The flashlight lay just beyond the violet fluttering of his hand.

Okay. He couldn't reach the drawer, his hand wouldn't get coherent signals if it left the field. I could let go of his ankle. He'd turn off the field when he got thirsty enough.

And if I didn't let go, he'd die in there.

It was like wrestling a dolphin one-handed. I hung on anyway, looking for a flaw in my reasoning. Peterfi's free leg seemed broken in at least two places ... I was about to let go when something must have jarred together in my head.

Faces of charred bone grinned derisively at me.

_Brain to hand: HANG ON! Don't you understand? He's trying to reach the flashlight!_

I hung on.

Presently Peterfi stopped thrashing. He lay on his side, his face and hands glowing blue. I was trying to decide whether he was playing possum when the blue light behind his face quietly went out.

* * * *

I let them in. They looked it over. Valpredo went off to search for a pole to reach the light switch. Ordaz asked, "Was it necessary to kill him?"

I pointed to the flashlight. He didn't get it.

"I was overconfident," I said. "I shouldn't have come in alone. He's already killed two people with that flashlight. The organleggers who gave him his new arm. He didn't want them talking, so he burned their faces off and then dragged them out onto a slidewalk. He probably tied them to the generator and then used the line to pull it. With the field on, the whole setup wouldn't weigh more than a couple of pounds."

"With a flashlight?" Ordaz pondered. "Of course. It would have been putting out five hundred times as much light. A good thing you thought of that in time."

"Well, I do spend more time dealing with these oddball science fiction devices than you do."

"And welcome to them," Ordaz said.