‘Well, no, it wasn’t what I’d planned. I wanted – Aislinn told me that when she was little her father used to take her to Powerscourt and they’d walk around the Japanese garden together, looking at the azaleas, and he’d tell her stories about a brave princess called Aislinn. So I wanted to see if I could find her an azalea plant. I thought . . .’ A tiny rueful smile, down at his hands. ‘I thought it would make her happy.’

‘That’s nice,’ I say, nodding. ‘Really nice. I’d say she’d have loved that.’

‘Now that,’ Breslin says approvingly, pointing his Biro at Rory, ‘that’s bringing your A game. That’s the kind of thing that gets a guy places, if you know what I mean. That might even have made up for those.’ The gloves. ‘Shame you screwed it up. I’m betting Tesco doesn’t stock azaleas.’

‘I know it doesn’t. But at that hour on a Saturday evening, nowhere else was going to be open. I thought even a bunch of ugly flowers was better than nothing.’ Rory glances anxiously between the two of us, looking for approval.

Breslin grimaces and wavers one hand. ‘Depends on the girl. If she’s the downmarket type, sure, but with this one . . . Never mind; too late now. So you headed up to Tesco . . . ?’

‘Yes. They didn’t have a lot of flowers left, and most of them were what you said – big daisies dyed strange colours – but I found a bunch of irises that were OK.’

‘Nothing wrong with irises,’ I say. ‘What time did you get to the Tesco?’

‘About quarter to eight. Maybe just after.’

And we can check that, too. CCTV on the bus, CCTV in the Tesco: the whole timeline Rory’s laying out is verifiable, and I wonder if that’s deliberate. Those forgotten flowers were very convenient. The Tesco is seven or eight minutes’ walk from Viking Gardens: just enough to account nice and neatly for that extra half-hour.

If Rory rushed there or back – and we need to go looking for someone who saw him rushing – he could have shaved a couple of minutes off that walk. The actual murder took almost no time: two seconds for the punch, maybe ten or twenty to check Aislinn’s breathing and her pulse, ten to turn off the cooker, gone inside a minute. It’s the build-up to the murder that could have taken time; if there was a build-up.

If Rory is our boy, he’s no routine rock-bottom-stupid wimp. He’s nervous, but he’s covering every crack before we can reach it, one step ahead all the way. If we’re stuck with him, then at least we’re gonna get a fight.

‘Cutting it a bit fine,’ I say. ‘How long were you there?’