Eleanor, the sister of sixteen, was next. Her mother offered to stay with her, but Eleanor declined, saying she’d manage alone. She appeared nervous, clasping and unclasping her hands. She asked what Karen had said. I explained it was better that we just concentrate on her and what she could tell me about Mary. She said she was sorry but she didn’t like her. That she bossed Karen around and upset her wee sister by saying there wasn’t a seat in heaven for her because she was a Protestant. She thought Mary was just hiding somewhere, so that everyone would look for her. Mary likes to be the centre of attention. And she flirts. With Alec up the road, even Eric. She halts there as though she’s said too much. Who’s Eric, does he live nearby too, I ask? She shakes her head. Eric’s my boyfriend. And he knows Mary? He doesn’t know her, she says firmly. But when he comes to collect me, she talks to him. Eleanor insists she isn’t worried and that Mary will turn up and get her picture in the papers, which is what she wants.

McNab paused there. He hadn’t met Karen’s big sister yet, although a couple of uniforms had taken an initial statement from her, the bare bones of which were that she hadn’t seen Karen or spoken to her since their parents’ funerals and she had no idea where Karen was living now. She thought Karen had married, although she hadn’t been invited to the wedding.

McNab recalled Robbie’s declaration that his family had been as happy as anyone else’s on that street. It seemed that wasn’t far from the truth.

The next piece, he realized, was McCreadie’s emotional take on the situation. McNab rarely, if ever, spoke about how the job affected him. Forty-five years ago, when the nature of policing was more gung-ho, he couldn’t imagine any officer openly revealing the personal impact of some of the horrors they’d had to face.

Yet here was McCreadie, doing just that.

I wish I could have met Mary McIntyre. (Let’s hope I will.) In the few photos taken of her, she seems to challenge the photographer. Bright, according to her teacher, Miss Stevens, likely to do well at secondary school, where she would go in August. There are some issues at home, her teacher says. A father who uses the belt on his children. Miss Stevens disapproves of using the belt in her classroom. Miss Stevens walked them to the chapel and she’s sure Mary was with them.

How the fuck do you talk to the parents of a missing child? They think you’re going to find her because you have to make them believe that. You’re determined to do that, while all the time you know. You just know that some bastard has her and is doing something to her right now, if he’s not already killed her. How do you keep that thought off your face?

The father, Dave, is the boss. No doubt about that. Evelyn, the mother, hovers round him, expecting to be swatted away like an annoying fly, but determined to be in his vicinity anyway. I suspect it’s a relationship I’ve seen often as a beat policeman. The one you walk past, despite the screaming. A domestic. Not our business. The famous belt is hanging there on the kitchen wall. He glances at it occasionally, as if to assure himself he’s still in charge.