I close my eyes. I know what he didn’t do. He didn’t lie to me. Not until later. Even then, he didn’t lie outright. To the police, yes, but never to me. ‘He killed Mary Trelease,’ I breathe. ‘Years ago.’ He was telling the truth when he told me that, at the Drummond Hotel. It was before I mentioned Abberton, before his confession had made me freeze, when he trusted me without reservation.

The woman I can only think of as Mary bends over me, using the gun to push her hair away from her face. ‘What Mary Trelease are you talking about?’ she asks. ‘Who do you mean?’

‘I don’t know.’

‘Exactly. None of this involves you. You should have gone away. I sent you away.’ I hear this as an accusation of ingratitude. She’s appalled by me. ‘Whatever you think you know, you’re wrong.’

Anger kicks in, as intense as the pain. ‘I know everything but who she was. She lived at 15 Megson Crescent. Aidan killed her there.’ In the front bedroom. Her naked, in the centre of the bed, Aidan’s hands round her throat . . .

‘He killed her, and let his stepfather take the blame,’ says Mary patiently, putting her face in front of mine so that I can see her telling me. ‘His stepfather’s been in prison for twenty-six years, and Aidan’s left him there to rot, never visited him or written to him, not once. How do you feel about him now, now that you know that?’ Her words drift past me without taking root.

‘The house,’ I say, my lungs aching with the effort. ‘That’s why you bought it. Why you changed your name to hers.’

Mary points the gun at my face. I close my eyes, wait for her to shoot, but nothing happens. When I open them, she hasn’t moved. Neither has the gun. ‘Why?’ she says.

I can’t answer. I don’t know how much blood I’ve lost, though the sensation of losing it is constant. I feel transparent. Hollow.

‘It’s up to you. You can talk or you can die.’

‘No! Please, don’t . . .’ I try to turn my head away from the gun.

‘Did you think that was a threat?’ She laughs. ‘I meant that if you talk, if you start to tell a story, you won’t let go until you get to the end. For your mind to keep working, your heart has to keep working. You have to stay alive.’