McCann would have been punching farther above than most, though. ‘If that was all she was after,’ I say, ‘she could’ve gone down to Copper Face Jack’s and had her pick of good-looking young fellas. Why him?’

‘Because she didn’t want some uniform who spent his day giving people hassle for not having their car tax up to date. Like we said before: after the life she’d had, she wanted thrills. She wanted a Murder D.’

I can see it. Murder are the big-game hunters; we spend our days going after the top predators. For these people, that makes us the top prey.

If that’s what Aislinn was after, Steve has a point: she didn’t have a lot of options. Murder is small: two dozen of us, give or take. Half are McCann’s age, or older. No one’s a supermodel.

All the same, I don’t believe she’d have picked out McCann. Going by Rory and the exes, rough and silent wasn’t her style. She would have skimmed straight over McCann and kept looking, gone for someone smoother around the edges, someone with a bit of chat to draw her in; someone like—

Someone like Breslin.

Breslin, with his lovely little wifey and three lovely little kiddies. Breslin, with plenty to lose if the badge bunny turned bunny-boiler. Breslin, pushing us to charge Rory Fallon and close the case.

I say, ‘Oh, Jesus.’

‘The only thing is the timing,’ Steve says. ‘If you’re right and Aislinn got McCann’s name off Gary, that was two and a half years ago. According to Lucy, she only picked up the secret boyfriend six months back. Why the gap?’

‘Try this,’ I say. ‘Aislinn goes to McCann looking for info, he gives her the brush-off. She doesn’t give up; every few months she’s back, hassling him for more. Then one day she turns up at the squad, he doesn’t feel like dealing with her, he sends his partner out to get rid of her for him. And Aislinn likes what she sees.’

Steve’s face has gone immobile. It changes him, strips away the studenty perkiness so that for once I can get a good look at what’s underneath. He’s turned adult, sharp, not someone to mess with.

I say, ‘Remember the neighbour who called in a guy going over Aislinn’s patio wall? Male, medium build, dark coat, probably middle-aged; and probably fair hair.’

Steve says, ‘Breslin the Monk. Having a full-on affair. You think?’

‘Everyone says Aislinn was something special, when it came to sucking people into her fantasies. The woman had talent, and she had practice. And Breslin, he overestimates himself and underestimates other people. Those are the ones who get tripped up. If she decided she wanted him . . .’

‘Yeah, but getting into something that risky? Breslin’s very careful of himself.’

‘He was careful. No calls, no texts, no e-mails, nothing. And remember how someone ran Aislinn through the system? Last September, right after she picked up her secret boyfriend? He was making sure she’d never been reported for stalking, harassment, blackmail, anything that said she might be a psycho.’