For everything George promised, only a fraction ever arrived. The clothes we wanted were little girl things-minuscule T-shirts and shorts. Instead of tampons, he gave us sanitary pads.

Slowly we collected more things. Pillows. A clock. Soap. New toothbrushes. Books. But whatever he gave us, he could take away. Tash didn't like asking, because she wasn't sure how he'd react. He could flip from being polite and caring to slamming his fist onto the table and telling her to "shut the f.u.c.k up!"

"Don't you know how lucky you are?" he'd scream. "I could have killed you. I could have buried you."

At other times, he'd wheedle and coax her, brushing her hair and fussing with her clothes. She kept him happy. She went upstairs when he asked and did what he asked, but I should have seen what was happening. I should have noticed the changes in Tash.

Whatever she ate upstairs made up for downstairs-where she ate nothing. She started biting her nails until they bled. She began losing weight. She stopped brushing her hair or cleaning her teeth.

When she cut up the magazines she created weird monsters, hybrids with animal heads and human bodies. And she stabbed out the eyes so they were empty.

Each time she climbed back down the ladder, there seemed to be less of her, as though George took a piece or she left it upstairs.

One night she wet the bed. I found her shivering in sodden clothes. Peeling them off, I heated water in a saucepan and washed her. She didn't say a word. Didn't cry. Didn't whimper.

"I think it's going to be a beautiful day," I told her. "I can hear the birds."

It was around that time that Tash came up with her plan. We were going to escape, she said, whispering because we couldn't be sure if George was watching or listening.

Tash pulled me beneath the ladder. "I'm going to do it with this," she said, reaching behind her back where she'd tucked something into her jeans. She unwrapped it carefully. "I found it upstairs when he wasn't looking."

It was an old screwdriver with a broken handle. Tash had bound the damaged end in an old rag so the sharp edges wouldn't cut her hand. She plunged it through the air in a stabbing motion.

"How are you going to do it?" I asked.

"I'm going to creep up behind him and stab him in the neck."

"What if he doesn't turn his back?"

"I'll pull him towards me and shove it into his guts... or in his eye."

"When?"

"Next time."

For hours she sat beneath the ladder and practiced, stabbing the metal tip into the wood, carving out her initials. At other times she lay on her bunk, listening. When the time comes, she said. When the time comes there will be no more time.

We waited, lying on our bunks, thinking our own thoughts.

"If something happens to me."

"Nothing is going to happen."

"If it does."

"It won't."

"Don't let him touch you, Piper."

"I won't."

"Do you understand?"

"Yes."

That's when we heard the furniture shifting and we knew George had come back. The trapdoor opened and we went through the routine with the water and food. He lowered a bucket and we emptied the bedpan.

Then it was time for Tash.

I couldn't see George's face in the darkness above. He was just a voice, like Morgan Freeman playing G.o.d in all those movies.

"I want Piper this time."

Tash looked at me. I was rocking from foot to foot, cold all over.

"Take me," she said.

"It's Piper's turn."

"No." Tash thought quickly. "It's her time of the month."

George didn't say anything for a while. Tash climbed the rough wooden ladder and raised her arms. Her cardigan rose up above the waistband of her jeans and I saw the screwdriver tucked against the small of her back.

I wanted to tell her not to do it. Don't risk it.

I sat down on the bunk and huddled against the back wall. Every shadow held a withered body.

I prayed. I don't pray very well. We're not a very religious family. My dad says nine out of ten religions fail in their first year.

While I was praying, I was listening, trying to hear what was happening upstairs. I imagined the worst things. Holes being dug and bodies buried. Hideous screams. That's what he always threatened to do: bury us deep where n.o.body would find us.

I don't know how long I waited. Dozing. Waking. Listening. I shouted at the ceiling.

"Give her back, you b.a.s.t.a.r.d! Don't you hurt her!"

I stood on the bench and looked out the crack in the window. There was a moon somewhere and I could just make out the trees and hear the wind moving the leaves.

I woke in the dark again, shivering violently. I sat up. Still alone. I reached across to her bunk. Felt her cold blankets. When I woke again it was almost light enough to see. I threw back the blankets and climbed the ladder, trying to balance, but I couldn't reach the trapdoor.

I stood on the bench. Looked through the crack. I could just make out a wire fence and the edge of another building with a broken window. Rubbish. Weeds. Silence. Nothing moving.

All the next day I waited. Time meant nothing. I was hungry and cold, but I wouldn't eat without Tash. I looked at the black eye on the ceiling. I begged him to give her back. I didn't want to be alone. I needed Tash.

Then I heard the sound of the hatch opening. Gaping darkly. He lowered her down to the ladder. Her legs didn't seem strong enough to support her. I stood beneath in case she fell.

Slowly she descended, flinching, pale. She had blood on the front of her dress. It had dried and darkened. She stumbled. I had to hold her up. Reaching the bunk, she curled into a ball and closed her eyes. Closed to me. Bleeding.

I made her a cup of tea. Heated some baked beans. She didn't eat. She didn't drink. She had stopped living by then. All hope gone.

11.

A sound has woken me: a creaking floorboard or a whispered voice outside the door. Maybe it wasn't a sound at all. Dull-headed, I push back the duvet and I tiptoe across the floor, joints popping in my knees.

Turning the latch, I glance along the hotel corridor. Empty. The darkness of the staircase is like an open void. I take a step and feel something wet under my feet. Melting snow, tracked in from outside. Someone has been standing here.

Closing the door, I turn the double lock and go to the window, pulling aside the curtains. It's still dark outside. Charlie is sleeping. She hardly makes a sound. When she was a baby I used to crouch over her cot, fearful that she wasn't breathing at all.

I won't sleep now. I will lie awake and go back over the details of yesterday. I cannot forget the image of the frozen girl. The more I try to push it away, the harder it pushes back. That is the grim inevitability of unwanted thoughts. We cannot empty our heads. We cannot forget.

I wake Charlie just after seven and we eat a quick breakfast before walking to the train station. Supplies for the journey-a take-away coffee, hot chocolate and the Daily Telegraph. Five minutes for the train.

Tires scorch into the station car park and a police car screeches to a halt. DCI Drury is out the door and sprinting up the steps, leaping the ticket barrier like a gymnast on parallel bars. Grievous struggles to catch up, straddling the barrier and grimacing in pain.

Drury storms along the platform. Breathless. Angry. He almost knocks Charlie over, before jabbing his finger into my chest.

"How in Christ's name did you know?"

I don't retreat, but I'm concerned for Charlie.

"Are you OK?" I ask.

She nods. I look at Drury. "Please apologize to my daughter."

He won't be distracted. "Tell me how you knew. Leece matched the dental records. It's Natasha McBain."

"I wasn't sure."

"Did Shaw recognize her?"

"No."

"How?"

"The dog."

"You're kidding me! You pulled a name out of your a.r.s.e based on a dog."

"It was more than that." I sound defensive.

"Where has she been? Three years and not a word, then she turns up in the middle of a blizzard."

"I don't know."

A train has appeared around a far bend, the carriages straightening, rails humming. For a moment the platform announcer interrupts. Drury waits, loosening his tie.

"You should have told me. I don't like being everybody's prize f.u.c.k."

"I could have been wrong."

"The chief constable wants to see you."

"Why?"

"That's his business."

"We're supposed to catch this train."

"There'll be others."

Chief Constable Thomas Fryer is a big man squeezed into a uniform that is one size too small for him. Pink-faced with jaundiced eyes, he has an office on the top floor of Thames Valley Police headquarters. It's a blue-sky view and daily affirmation that he's reached the top of his chosen profession.

Removing his rimless gla.s.ses, he wipes them with a Kleenex.

"DCI Drury wants to have you arrested."

"On what grounds?"

"You've made him look foolish."

"That wasn't my intention."

Through the vertical blinds, I can see the outer office. Charlie is waiting for me, sitting on a plastic chair, texting on her iPhone. Drury is in the same room, pacing the floor, furious at being excluded from the meeting.

Fryer puts on his gla.s.ses.

"He's a good detective. Hot-headed. Noisy. But he gets results."

The chief constable takes a seat. The silver b.u.t.tons on his uniform rattle against the metal edge of his desk.

"Are you a gambling man, Professor?"

"No."

"But you understand odds?"

"Yes."

"A true punter might wager a few quid on a long shot just to keep an interest in a race, but he doesn't bet his house on an outsider without inside information, you understand what I'm saying?"

The answer is no, but I don't interrupt him.