When I was a young resident at a hospital in London, a five-year-old boy was brought into the Emergency Department. His brother had shut him in the chest freezer in their garage after a quarrel. The boy had been in there for four hours before he was found by his distraught father. Hypothermia had slowed his metabolism and reduced his oxygen usage, which was the only reason he hadn’t suffocated. He had severe frostbite on his fingers and facial extremities – nose, ears – but he survived.

Brain-damaged. Unable to see or hear or walk or talk.

‘Explain it to me, Stacey,’ I say reasonably. ‘Why does it benefit you to do this to him? To us?’

‘I didn’t have a choice,’ she says, sounding almost apologetic. ‘Sooner or later, Peter would have talked about Felix. I could have just left your son down here, and you’d never have known what happened to him, but I thought you deserved better than that. I thought you’d want to be with him.’

‘He’s ten, Stacey. Who’d have believed him?’

‘You,’ she says.

I try not to look at the freezer, try very hard not to think of my son, my child, curled up inside. ‘I have very little credibility with the police where you’re concerned,’ I say. ‘We had a deal before. You could leave the country as you planned. I won’t say anything because that’d just incriminate Peter.’

‘What about Felix?’

‘What about him? You could leave him here. No one knows this cellar exists. Or I could help you move his body. I’d be implicated, then, too. We’d be partners in crime. I couldn’t say anything even if I wanted to.’ I force a laugh. ‘You could sell me the Glass House after all and it could be our secret.’

She’s tempted. I can see it in her eyes.

‘It’s the perfect crime,’ I say. ‘You actually got the victim to collaborate in his own murder. It’s brilliant. Because you intended to kill him all along, didn’t you?’ I smile conspiratorially. ‘I think we both know he was never going to walk out of here. It’s why you told Peter, isn’t it? You wanted someone to appreciate the beauty of it all. Everyone wants their work respected.’

‘Felix wasn’t a victim,’ Stacey says, ‘whatever he told your husband. He was with me because he wanted to be. He needed me. And defrauding Copper Beech was his idea. Except he didn’t think it through, as usual. I was the one who had to step in and sort out his mess.’

‘I’m not the enemy, Stacey,’ I say.

‘It’s too late,’ she says impatiently. ‘I don’t have time for this.’

‘At least let Peter—’

‘Don’t be boring, Millie. You’ve always been so much better than that.’