There was even a term for it, family destruction. Usually it was a murder-suicide, often triggered by a catastrophic work failure, but in this case David’s crazed brain had told him I was the answer, the teenage nanny. That we could start a new life together. Maybe I was to blame for that, maybe I’d led him on, in my loneliness. Maybe that’s why I never said what had really happened. Or maybe I was just too afraid to admit my own guilt, throw myself on the mercy of a foreign justice system.

‘When I got back, they were already dead – your mum and Madison. I couldn’t let him take you too.’

‘You shot him. For me.’

‘I – had to. And look at you!’ I was crying. I was smiling too. He was alive, he was grown up, he was here. ‘I’d do it again, Carson. If I had to.’

He shook himself, as if realising the situation anew. The two of us on the cold lake shore, soaking wet, a dead man at our feet. ‘Come on. We’d better deal with this before someone comes.’

I looked again at Alex’s body. He had murdered Stacey Donner and Anna, and he would have murdered me. Despite everything, I knew I had done what I had to and could not regret it, not really.

Carson was looking around. ‘Are there cameras in the shelter?’

‘Um, just at the front, not out here.’ Dog thieves were a real risk in the area.

‘Good. So we just need to weigh him down.’

Between us, we somehow worked it out, though we were both shaking with shock and cold. We filled Alex’s jeans pockets with rocks. I piled them under his T-shirt too, on top of the chest where I’d once loved to rest my head. I tried not to think about it, the way his blank eyes reflected the moonlight, the wind whipping his lifeless hair. I just did the job. We dragged his body further out into the lake, and let him drift into the darkness. For a moment I was afraid he wouldn’t go under, then his clothes filled up with water and he sank, slowly, out of sight. This lake was deep and dark. He might never be found.

We splashed back to the lake shore, puffing and panting, soaked through. We were both smeared in blood. There was even a faint trail of it back up to the shelter.

‘Look,’ I said. ‘It’s no use. There’s too much evidence.’

But Carson never faltered. ‘They won’t suspect me. It’s all about how it looks, Casey. Alex must have been a suspect too – they always look at the husband. So they’ll think he was guilty, that he disappeared. We just need to clean up this blood. Bleach, that hides blood, I think. There’s lots on the forums about it.’