I HELD LITTLE BEE for a long time. Then I asked her: Will you go down and play with Charlie and Lawrence? I have to make a phone call.

After she walked down the stone steps, I held on to the iron railing of the embankment and I held on to my memories of Andrew and I held on to my mobile phone. The phone was shaking in my hand, showing five bars of signal. The reception was so strong in the center of London, one hardly needed the handset at all. The air positively crackled with connectivity, as if one might simply direct a thought at someone and be received loud and clear. My tummy lurched and I decided, Right, I’ll do it now, before I calm down and change my mind. I called the publisher and told him I didn’t want to edit his magazine anymore.

What the publisher said was, Fine.

I said, I’m not sure you heard me. Something extraordinary has happened in my life, and I really need to run with it. So I need to quit the job. And he said, Yeah, I heard you, that’s fine, I’ll get someone else. And he hung up.

And I said, Oh.

I stood there for a minute, shocked, and then I just had to smile.

The sun was lovely. I closed my eyes and let the breeze air-brush away the traces of the last few years. One phone call: I realized it was as simple as that. People wonder how they are ever going to change their lives, but really it is frighteningly easy.

I was already thinking about how I might carry on with Andrew’s book. The trick, of course, would be to keep it impersonal. I wondered if that had been a problem for Andrew. He never liked to put himself in the story.

But what if the story is that we are in the story? I started to understand how Andrew must have agonized over it. I wondered if that was why he had kept so quiet.

Dear Andrew, I thought. How is it that I feel closer to you now than I did on the day we were married? And after I just told Little Bee I didn’t want to hear what she had to say because I know I need to stick with Lawrence. This is the forked tongue of grief again. It whispers in one ear: return to what you once loved best, and in the other ear it whispers, move on.

My phone went, and my eyes snapped open. It was Clarissa.

“Sarah? They just told me you resigned. Are you crazy?”

“I told you I was thinking about it.”

“Sarah, I spend a lot of time thinking about bedding Premiership footballers.”

“Maybe you should try it.”

“Or maybe you should come in to the office, right now, and tell the publishers you’re very sorry, and that you’re going through a bereavement at the moment, and please—pretty please—could you have your nice job back.”

“But I don’t want that job. I want to be a journalist again. I want to make a difference in the world.”

“Everyone wants to make a difference, Sarah, but there’s a time and place. Do you know what you’re doing, honestly, if you throw your toys out of the pram like this? You’re just having a midlife crisis. You’re no different from the middle-aged man who buys a red car and shags the babysitter.”

I thought about it. The breeze seemed colder now. There were goose bumps on my arms.

“Sarah?”

“Oh Clarissa, you’re right, I’m confused. Do you think I’ve just chucked my life away?”

“I just want you to think about it. Will you, Sarah?”

“All right.”

“And call me?”

“I will. Clarissa?”

“Darling?”

“Thank you.”

I hung up and looked out over the river. When we first arrived the water had been flowing downstream toward the wild estuary and the untamed waters of the North Sea. Now it was nudging back in the direction of Oxford and the crisp white boathouses of Henley. It is hard, when it comes right down to the actual choice, to know what you want out of life.

I went down the stone steps to the little shrinking beach. I said to Lawrence and Little Bee, I called work. I’ve got something to tell you both. But they looked so forlorn, standing there, standing apart from each other, not speaking. I realized this was never going to work.

I thought, Oh gosh, how foolish I’ve been.

I have always struck myself as a very practical woman, capable of adaptation. I immediately thought, I’ll phone the publisher and tell him I made a mistake. And not just a little mistake but a great, elemental, whole-life mistake. During one whole week of grace I utterly forgot, you see, that I was a sensible girl from Surrey. It was something about Little Bee’s smile, and her energy, that made me sort of fall in love with her. And thus love makes fools of us all. For a whole week I actually thought I was a better person, someone who could make a difference. It completely slipped my mind that I was a quiet, practical, bereaved woman who focused very hard on her job. Isn’t that odd? I’m awfully sorry. And now might I please have my old life back?

I held out my hands to Little Bee and Lawrence, but then I noticed that Charlie was no longer with them.

“Um, where’s Charlie?”

It is painful to think about this time, even now.

What did I do? I looked all around, of course. I ran up and down. I began screaming Charlie’s name. I raced up and down the shrinking beach, staring into the face of every child playing there in case it should somehow transform into mine. I shouted myself hoarse. My son was nowhere.

An aching panic took me over. The sophisticated parts of my mind shut down, the parts that might be capable of thought. I suppose the blood supply to them had been summarily turned off, and diverted to the eyes, the legs, the lungs. I looked, I ran, I screamed. And all the time in my heart it was growing: the unspeakable certainty that someone had taken Charlie.

At the other end of the little beach was a second set of steps leading up the embankment wall, and I ran up them. Camped out on the top step was a picnicking family. The mother—long auburn hair with rather frazzled ends—sat cross-legged and barefoot, surrounded by the peelings and the uneaten segments of satsumas. She was reading BBC Music Magazine. She had it spread out on the rug, pinned down with one foot to stop the pages blowing. There was a slender silver ring on her second toe. Beside her on the step, two flame-haired girls in blue gingham dresses were eating Kraft cheese slices straight from the packet. The husband, blond and stocky, stood a few feet away, leaning on the railing and talking into his mobile. Lanzarote’s just a tourist trap these days, he was saying. You should go somewhere off the beaten track, like Croatia or Marrakech. Your money goes further there in any case. I was out of breath. The mother looked up at me.

“Is everything alright?” she said.

“I’ve lost my son.”

She looked at me blankly. I smiled idiotically. I didn’t know what to do with my face. My mind and my body were keyed up to fight with pedophiles and wolves. Confronted with these ordinary people in this absurdly pleasant tableau, ringed all around by strolling tourists, my distress seemed desperate and vulgar. My social conditioning fought against my panic. I felt ashamed. Instinctively, I also knew that I needed to speak to the woman calmly, in her register, if I was to communicate clearly and get across the information I needed without wasting any time. I have struggled all my life to find the correct point of balance between nicety and hysteria.

“I’m very sorry,” I said, “I’ve lost my son.”

The woman stood up and looked around at the crowd. I couldn’t understand why her movements were so slow. It seemed that I was operating in air, while she occupied some more viscous medium.

“He’s about this high,” I said. “You’d have noticed him, he’s dressed as Batman. Did he come up these steps?”

“I’m sorry,” she said in slow motion. “I haven’t seen anything.”

Each word took forever to form. It felt like waiting for the woman to engrave the sentence in stone. I was already halfway back down the steps before she finished speaking. Behind me I heard the husband saying, You could always go for the cheapest package tour and just use the flights. Then you can find some nicer accommodation once you’re out there.

I ran back down the steps, shouting Charlie’s name. Somehow I arrived back at the place where Charlie had built his sand castles. I kicked the structures apart, shouting his name. While parents and children looked on aghast, I looked for my son under piles of sand as little as six inches high. Of course I knew Charlie wasn’t underneath. I knew, even as I was scrabbling away at anything that protruded. I found an old crisp packet. The broken wheel of a pushchair. My nails bled into a barely submerged history of tides.

Little Bee and Lawrence stared at me, wide-eyed, and I remember the last rational thought that went through my mind: He isn’t on the sand, and he didn’t go up the steps, so he must be in the river. Even as I thought it, I could feel the second stage of my mind shutting down. The panic simply rose up out of my chest to engulf me. I splashed out into the Thames, knee-high, then waist-high, staring down into the muddy brown water, screaming Charlie’s name at the floating plastic bags and the startled gulls.

I saw something under the water, lying on the muddy sludge. Underwater, distorted by ripples, it looked like a bone-white face. I reached down and grabbed for it. I lifted it up into the bright day. It was a cracked plastic mask from a tourist stand, with its snapped elastic showing how it had blown into the river. As I held it up, dripping muddy water, I realized that my phone had been in the hand I held the mask in. My phone was gone, somewhere—my life was gone—lost in the sand or the river. I stood in the water, holding a mask. I didn’t know what to do now. I heard a whistling sound and I looked down sharply. I understood that the breeze was whistling through the empty eyeholes of the mask, and that is when I truly began to scream.

Charlie O’Rourke. Four years old. Batman. What went through my mind? His perfect little white teeth. His look of fierce concentration when he was dispatching baddies. The way he hugged me, once, when I was sad. The way, since Africa, that I had been running between worlds—between Andrew and Lawrence, between Little Bee and my job—running everywhere except to the world where I belonged. Why had I never run to Charlie? I screamed at myself. My son, my beautiful boy. Gone, gone. He had disappeared as he had lived, while I was looking the other way. I looked at the empty days before me, and there was no end to them.

My voice sank to a whisper. I breathed Charlie’s name.

Then I felt hands on my shoulders. It was Lawrence.

“We need to be systematic about this now,” he said. “Sarah, you stay here and keep calling for him, so he knows where to come back to if he’s wandering. I’ll go and ask people to start looking, and I’ll keep looking myself. And Bee, you take my phone and you go up on the embankment and you call the police. Then you wait for them, so you can show them where we are when they arrive.”

Lawrence handed his phone to Little Bee, and turned back to me. I stared at him dumbly.

“I know it sounds extreme,” he said, “but the police are good at this. I’m sure we’ll find Charlie before they get here, but just on the off chance that we don’t, it makes sense for us to bring them in sooner rather than later.”

“Okay, do it,” I said. “Do it now.”

Little Bee was still standing there, holding Lawrence’s phone in her hand, staring at Lawrence and me with large and frightened eyes. I couldn’t understand why she wasn’t already running.

“Go!” I said.

She still stared at me. “The police…,” she said.

Understanding buzzed dully in my mind. The number. Of course! She didn’t know the emergency number.

“The number is 999,” I said.

She just stood there. I couldn’t work out what the problem was.

“The police, Sarah,” she said.

I stared at her. Her eyes were pleading. She looked terrified. And then, very slowly, her face changed. It became firm, resolved. She took a deep breath, and she nodded at me. She turned, slowly at first and then very fast, and she ran up the steps to the embankment. When she was halfway up, Lawrence raised a hand to his mouth.

“Oh shit, the police,” he said.

“What?”

He shook his head.

“Never mind.”

Lawrence ran off. I began shouting again for Charlie. I called and called, while the tourists stared, and the breeze left me shivering in my wet jeans. At first I called out Charlie’s name as a sound for him to home in on, but as my voice began to go I realized that another line had been crossed and I was shouting the name just to hear it, to ensure its continuing existence. I realized that the name was all I had in the world.

Then a voice came from behind me. It was Lawrence.

“Sarah?” he said. “It’s okay. I found him.”

Lawrence held Charlie in his arms. My son was filthy, and his bat cape hung straight down, heavy with water. I ran to him, took him into my arms and held him. I pressed my face into his neck and I breathed in his smell, the sharp salt of his sweat and the sewer tang of the dirt. The tears streamed down my face.

“Charlie,” I whispered. “Oh my world, my whole world.”

“Get off, Mummy! You’re squashing me!”

“Where were you?”

Charlie held out his hands to the sides, palms upward, and answered me as if I was simple.

“In mine bat cave.”

Lawrence grinned and pointed at the wall of the embankment.

“He was right inside one of those drainage pipes.”

“Oh Charlie. Didn’t you hear us all shouting? Didn’t you see us all looking for you?”

Charlie grinned beneath his bat mask.

“I was hiding,” he said.

“Why? Why didn’t you come out? Couldn’t you see how worried we all were?”

My son looked forlornly at the ground. “Lawrence and Bee was all cross and they wasn’t playing with me. So I went into mine bat cave.”

“Oh Charlie. Mummy’s been so confused. So terribly silly and selfish. I promise you, Charlie, I’ll never be so silly again. You’re my whole world, you know that? I’ll never forget that again. Do you know how much you mean to me?”

Charlie blinked at me, sensing an opportunity.

“Can I have an ice cream?” he said.

I hugged my son. I felt his warm, sleepy breath on my neck, and through the thin gray fabric of his costume I felt the gentle, insistent pressure of the bones beneath his skin.

I looked up at Lawrence and I said, Thank you.