I received them. I asked Dad – my real father, you understand, and not the rot in my bones – to destroy each one when it arrived. They were easy to identify; they came resealed, with a stamped warning of correspondence from an inmate at HM Prison Northwood. Soon after my twenty-first birthday, when I was home from university, Dad came to me with a confession and a box, and all of the fucking letters stuffed inside. ‘I just thought,’ he said, ‘that in the future – you may be curious—’ It must have been the winter holidays, because the barbeque was in the garden shed; he helped me to wheel it out, and we stood in our coats, him with his pipe and me with a cup of tea, and posted them into the fire.

‘I think that you’re in the wrong story,’ I said to the chaplain. ‘There’s a narrative – you see it a lot – which builds up to a prison visit. Somebody inside, they’re waiting for somebody else to visit. To be forgiven. The visitor’s been mulling it over for years, and they can’t decide whether to do it. Well. In the end they go. It’s usually a parent and a child, or maybe a perpetrator and a victim – it depends. But they go. And they have a conversation. And even if the visitor doesn’t forgive the person, exactly, they at least take something from the whole thing. But, you see – my mother’s dead. And I never did visit.’

I had the mortifying sense that I was going to cry, and I pulled my sunglasses down to hide it. The chaplain became a lumpy white spectre in the darkness. ‘I’m sorry that I can’t help you,’ I said, absurdly, and stumbled back down the aisle. The sun was finally starting to soften, and now it was time for a drink. I thought of a hotel bar and the weight of the first glass, settling heavy across my limbs. The warden’s assistant was waiting for me.

‘Are we all done?’ she asked. Our shadows were long and black on the tarmac, and when I reached her they became one strange beast. Her shift was probably over.

‘Yes,’ I said. ‘I should go.’

In the car, I checked my phone. Is there such a thing, Olivia had texted, as too jovial?

I held Mother’s cardboard box in my lap and lifted the lid. A ragtag of possessions. There was a Bible, predictably. There was a hairbrush. There were two clippings, sticky with tape, which had been torn from magazines: one was an advertisement for beach holidays in Mexico, and one was for nappies, with a little row of clean, happy children laid out on a white blanket. There was a newspaper cutting about Ethan’s charity work in Oxford. There were three chocolate bars, and a lipstick which was nearly finished. As usual, she gave nothing away.

The last time I saw Mother was the day that we escaped. That morning I woke up in the soiled bed and knew that my days had run out, and that if I didn’t act then this was where I would die.

Sometimes, in my head, I visit our little room. There are two single beds, pressed into opposite corners, as far away from one another as they can be. My bed and Evie’s bed. The bare bulb hangs between them, twitching at footsteps in the hallway outside. It is usually dull, but sometimes, if Father decides, left on for days. He has sealed a flattened cardboard box against the window, intending to control time, but a dim, brown light seeps through and grants us our days and our nights. Beyond the cardboard there was once a garden, and beyond that, the moor. It has become harder to believe that those places, with their wildness and their weather, could still exist. In the peaty glow, you can see the two-metre Territory between the beds, which Evie and I know better than any other. We have discussed the navigation from my bed to hers for many months: we know how to traverse the rolling hills of plastic bags, bulging with items which we can’t remember; we know that you would use a plastic fork to cross the Bowl Swamps, which are blackened and congealed, and close to drying out; we have debated the best way to pass through the Polyester Peaks to avoid the worst of the filth: whether to take the high passes and risk the elements, or to pass through the tunnels of rotting materials beneath them and face whatever may be waiting there.

I had wet myself again in the night. I flexed my toes, twisted my ankles, and kicked my legs as if I was swimming, as I had done every morning for the last few months. Two. Maybe three. I said to the room what I would say to the first person I met when I was free: My name is Alexandra Gracie, and I am fifteen years old. I need you to ring the police. Then, as I did each morning, I turned to see Evie.

We had once been chained in the same direction, so that I could see her all of the time. Now she was tied away from me, and we both had to contort our bodies to meet eyes. Instead I could see her feet and the bones of her legs. The skin burrowed into each groove, as if searching for warmth there.

Evie spoke less and less. I cajoled her and shouted at her; I reassured her, and sung the songs which we had heard when we still went to school. ‘Your part,’ I said. ‘Are you ready for your part?’ None of it worked. Now, instead of teaching her numbers, I recited them to myself. I told her stories in the darkness and heard no laughter, or questions, or surprise; there was just the quiet space of the Territory and her shallow breathing, rushing across it.

‘Evie,’ I said. ‘Eve. Today’s the day.’

I drove back to the city through the early dusk. A thick golden light fell between the trees and across the open fields, but in the shadows of the villages and the farmhouses it was already dark. I contemplated driving through the night and hitting London before sunrise. Jet lag made the landscape bright and strange. I would probably end up asleep on a roadside in the Midlands; it didn’t seem such a good idea. I stopped in a lay-by and booked a Manchester hotel with vacancies and air conditioning.