‘You will be a big help to me in the house,’ Thea said. ‘And the doctor is working on a wonderful research project. You will be able to help with that too.’

I was sure she was referring to the doctor’s exploration of the origins of evil, using me as his source material, and I shuddered at the thought. But what choice do I really have?

The two other women were in their rooms when I returned. I wanted to talk to them, to find out whether they too had been forced to make such a difficult decision, but I don’t know if I can trust them. I still haven’t asked the girl who has the room opposite me why she has a photograph of Paul in her diary.

I was about to go into my room when I heard muffled crying from across the corridor, and I thought maybe I had upset the girl by asking too many questions earlier. I remembered what she had said to me: ‘I don’t know why I did it.’ ‘I loved him.’ ‘I took him.’ But I still didn’t know what she was talking about, so I knocked softly on her door and pushed it open.

‘Are you okay?’ I asked – a silly question, given her blotchy cheeks and bloodshot eyes. ‘I’m sorry if I made you remember something you would rather forget.’

She gave a choked laugh. ‘I can’t forget. The problem is, I can’t remember either.’

‘Do you want to tell me about it?’ I asked, not for the first time.

‘I’ve told you,’ she said.

‘You said you took him and you loved him. But I don’t know who you mean.’

‘I took the baby – Albie. I took him.’ She seemed to be getting slightly hysterical so I sat down and put my arm around her again, pulling her close to me.

We talked about it for a long time, and gradually her story came out – how she had been working as a nanny for a couple who had a baby called Albie, a baby she had dearly loved. And then, for some reason that she couldn’t explain to herself, she had abducted the child. She had brought him here and asked Thea and the doctor to help her keep him as her own. Thea had immediately taken control of the situation, and the baby had been safely returned to his parents. She didn’t explain how, but she was so distressed that I didn’t want to make things worse by asking. Thea and Garrick had been sheltering her here ever since, safe from prosecution for what she had done.

Finally, as I rocked her slowly backwards and forwards, she started to drift and I realised she was falling asleep. I helped her into bed and pulled the covers over her, as if tucking in a child.