Me and Steve let that lie just long enough, and come just close enough to looking at each other, that McCann gets edgy. ‘What?’ he demands.

‘The affair,’ I say. ‘That began in September?’

‘The beginning of September. Yeah.’

‘Date.’

‘I don’t remember.’

I’ve made him lie, rather than sound like the sap who’s clinging on to every tiny detail, and he knows we know. I let a flicker of a smile slip through, and see his jaw muscle roll.

‘We’ll leave it at the beginning of September,’ I say, being generous, which gets another twitch of his jaw. ‘And it kept going till last weekend. Any breakups along the way, anything like that?’

McCann has his arms folded again; his cop face is back, a flat slab. ‘No. No problems. No arguments. Everything was great.’

‘Autumn,’ Steve says thoughtfully, examining his Biro. ‘Winter. And not being crude, but you two weren’t just chatting any more. I’d say the picnics up the mountains weren’t doing the job for yous, were they? Where’d you meet?’

None of your business grits McCann’s teeth, but he says, ‘Her place.’

Steve frowns. ‘None of the neighbours ever saw you.’

‘Because I didn’t want them seeing me. I went down the laneway behind Aislinn’s house, over the wall, in by the back door. She gave me a key.’

And there’s the autumn intruder. ‘Fair play to you, climbing walls at your age,’ I say, almost holding back a grin – McCann doesn’t like that either. ‘Better than the gym any day. How often were you there?’

He’d love to lie about that, but he can’t risk it. ‘A couple of times a week. It depended. On work, my family, all that.’

‘How’d you make the appointments?’

‘Sometimes we’d make plans for next time before I headed off. Other times I’d leave her a note saying when I could call round. Or if I got a free hour or two I wasn’t expecting, I’d just go round to her.’

‘Where’d you leave the notes?’

‘Post-it in a 7-Up bottle, throw it over her back wall. She knew to check.’

‘We didn’t find any Post-its in the house.’

‘I’d take them back when I got there. Get rid of them.’

I do startled. ‘Why?’

‘Why do you think? Because I’ve been in this job too long to leave evidence floating around.’

The cold flat glance says And way too long to get tied in knots by the likes of you. ‘Jaysus,’ I say. ‘Lot of hassle for the odd shag.’

‘Depends how good of a shag.’ That nasty grin again, but I’ve seen McCann use it on suspects and it doesn’t work on me.

‘Why not ring Aislinn, or text her? Your number wasn’t even on her phone. Why not?’

‘Because I didn’t want it there.’

‘And why not go in her front door like a normal person?’

He eyes me with dislike. ‘Why the hell do you think?’