‘The police are investigating,’ Mark says. ‘They said it might be a few weeks until we hear any more. We’re not to share the news with anyone outside the family and you mustn’t breathe a word on Facebook.’

The clock tick ticks in the corner of the room like a clockwork mechanism being wound inside my son. I brace myself, waiting for an explosion of rage and fury to burst from him.

None comes.

He bends at the knees and I feel sure that he’s going to collapse but then he plucks the slice of meat and the shred of lettuce from the carpet and tucks them back into the polystyrene container. He closes it, his large hands fumbling the squeaky plastic lip back into the box, then he turns and walks up the stairs, taking them one at a time.

Chapter 30

Unlike the counsellor the police arranged for me to see after Billy disappeared, Sonia works from home. We’re sitting in the back room of her terraced house in Bedminster. Not in an office block in town. It is a bright and airy room, decorated in shades of brown and beige with little touches of orange – the cushions on the sofa, the lampshade of the standard lamp in the corner of the room and a single white hydrangea in a vase above the black iron fireplace. On first glance it looks like a living room but it’s too carefully arranged. There are no children’s toys picking up dust under the sofa, no books propped open on the arm of the chair and no abandoned Diet Coke can on the table in the middle of the room. It’s homely but there are no traces of Sonia’s personality. I imagine that’s deliberate.

Mark didn’t go to work yesterday. Neither did Jake. I could hear him and Kira talking in low voices behind their closed bedroom door when I went to the bathroom a little after 7 a.m.

Mark and I stayed up in the living room for hours on Friday night. We both cried, taking it in turns to hold and console each other, whispering platitudes like, ‘We’ve been through worse,’ ‘We can get through this,’ and ‘There’s been a mix-up. Jason Davies has confused our son with some other family’s child.’