Steve brushes at the wall and sits down beside me. ‘Just legged it. He got a message from some girl in Howth?’

‘Yeah. She’s not gonna be much use to him. You have lunch yet?’

‘Nah.’

‘Here.’

I pass him the other sandwich. Steve takes it and holds it in his two hands, not opening it. ‘Did you get anything good?’

‘Tentative ID off the barman. No joy out of the uniform. Sophie’s guys got a male DNA profile off the mattress.’

He says, ‘What do we do?’

I say, ‘We need to talk to McCann.’

There isn’t a way around it any longer. In two hours, maybe three, Breslin will be back and suspicious and wanting to arrest Rory. Those couple of hours are all we’ve got.

Steve nods. He asks, ‘How?’

We have so many weapons. You pick them up from watching other Ds, you sift them out of squad-room stories, you come up with your own and pass them around; you stash them all away safe, for the days when you’ll need them. By the time you make Murder, you have an arsenal that could pulverise cities.