Steve says, ‘We focus on the relationship. Nothing else. We don’t go near Breslin being involved, or McCann’ll go loyal and shut his trap. Just talk about Aislinn.’

‘We’ve got one grenade,’ I say. ‘When Breslin found out that file box was full of the Desmond Murray case, he was relieved. Meaning he didn’t know McCann had worked that case. Meaning two days ago, at least, McCann hadn’t made the connection: he didn’t know Aislinn was Des Murray’s daughter. He didn’t know she was playing him all along.’

Steve says, ‘We save that.’

‘Yeah. That oughta go off with a bang.’

The birds have forgotten their fright and come back to peck about on the grass. Breslin is across the river by now, heading north.

Steve asks, ‘Where do we do it?’

This is what I was thinking about, all the way back here in the car, all the time I was waiting for Steve. ‘Interview room,’ I say.

His face turns towards me. ‘You think? We could clear out the incident room. Or come out here, even.’

‘No. We throw everyone out of the incident room, we might as well put up a sign saying there’s some big secret thing going down. Anyway, from now on we need to document everything, if we want a snowball’s chance in hell of making a case.’

‘He’ll know. The second we head for an interview room, he’ll know.’

‘He will anyway. No matter where we take him, there’s no way we can make this seem like a nice friendly chat, not past the first thirty seconds. The moment we bring up him having met Aislinn, he’s gonna know.’

The thought of that moment flicks across us like a small black splatter of sleet. It stops us talking.

We get the sandwiches down us, the Coke for caffeine. Then we go into the Murder building, in through the glossy black door with the combination my fingers could press in my sleep, nodding to Bernadette on our way past. We take off our coats and hang them neatly in our lockers, I take off my satchel and stash it away. Steve finds a copy of the family photo from the Desmond Murray case and tucks it in his suit pocket; I take photos of the arrays, on my phone, and then I shove them to the bottom of my locker and hope no one picks today to piss in it again. The twin metal slams of our locker doors echo, sharp and startled, against the tiles of the small dim room.

We go side by side up the wide marble staircase, our footsteps circling blurrily around the stairwell, to the squad room. We go in there with no stack of papers, no videocassettes, no voice recorders. We go in with our hands empty.