‘I don’t want to be on my own.’

‘You won’t be. I’ll stay and look after you till she comes back. Do you think you can go back to bed now? Mum will be here when you wake up. I promise.’

I feel a trickle of cold slither through my veins. I made that promise to Lottie not so long ago. I should learn from my mistakes.

Once Kai has plodded back upstairs, I go into the kitchen and put the kettle on. Anna hasn’t tidied away her supper things. There’s a glass on the side, its bowl stained with the evaporated residue of red wine, and her supper plate is still on the table. I almost tidy them away but change my mind and leave them where I find them, in case she thinks I’m making some kind of point. The sort of thing Cora does. I touch the In-Step app on my phone and open groups. Anna’s done two thousand three hundred and sixty-seven steps today. That’s about one and a half kilometres in In-Step-speak. She’s not walking now. Maybe her phone is lying switched off beside someone else’s bed, or in her bag, slung over a chair in someone else’s kitchen. As distressed as I am at the neglect this implies, I hope this is the case.

I have a look round. She’s finished Thomas’s chair and started on the next one, lightly pencilling in the name ‘William’ with a stencil. I chew my lip. I have an opportunity here. I need evidence that Anna was expecting to see Nick that Saturday night, that she lay in wait for him, and that Nick is the reason she moved here. If someone comes to the door and I’m downstairs I can hit the sofa; if I’m upstairs, I can get into her bed and pretend to be asleep. Anna will be bewildered, possibly cross, but she won’t be able to say anything. She’s the one who’s left her ten-year-old alone because she doesn’t want to pay a babysitter while she’s on a date; I’m almost certain that’s what it is. I expect it’s unusual for Kai to wake up in the night and she thought she could get away with it.

I start in the kitchen, working my way through the cabinets. I move into the dining area where there’s an old dresser. The drawers contain paper, sketchbooks, crayons and felt-tip pens. Kai likes to draw seascapes full of weird and wonderful creatures.