Conway snapped her fingers in my face. ‘Focus.’

I said, ‘What do the boarders sleep in? Dorms or single rooms?’

‘First- and second-years, six to a dorm. Third- and fourth-years, four to a room. Fifth- and sixth-years, two to a room. So yeah, you’d have at least one roommate to worry about, if you were sneaking out. But here’s the thing: from third year up, you get to choose who you share with. So whoever’s in your room, chances are they’re already on your side.’

Down the side of the tennis court – nets loose, couple of balls rolled into a corner. I still felt the school windows staring at my back. ‘How many boarders are there?’

‘Sixty-odd. But we narrowed it down. The nurse gave some kid the key on a Tuesday morning, kid brought it straight back. Friday lunchtime, someone else asks for it and it’s gone. The nurse’s office is locked when she’s not there – she swears she managed to get that right, at least, stop anyone from mainlining Benylin or whatever she keeps in there. So if someone nicked the key, it was someone who was in to the nurse between Tuesday and Friday.’

Conway shoved a branch out of her way and headed down one of the little paths, deeper into the grounds. Bees working away at apple blossom. Birds up above, not rattly magpies, just little happy birds getting the gossip.

‘The nurse’s log said there were four of those. Kid called Emmeline Locke-Blaney, first-year, boarder; she was so petrified of us she practically wet herself, I don’t see her being able to keep anything back. Catríona Morgan, fifth-year, day girl – which doesn’t rule her out, she could’ve passed the key on to a mate who boarded, but they clique up pretty tight; day girls and boarders don’t really mix, don’tchaknow.’ A year on, every name off by heart, easy as that. Chris Harper had got to her, all right. ‘Alison Muldoon, third-year, boarder – one of Heffernan’s little bitches. And Rebecca O’Mara.’

I said, ‘Holly Mackey’s gang again.’

‘Yeah. See why I’m not convinced your little buddy’s telling you everything?’

‘Their reasons for going to the nurse. Did they check out?’

‘Emmeline was the only one with a verifiable reason: sprained her ankle playing hockey or polo or whatever, needed it strapped. The other three had headaches or period cramps or dizzy fits or some bullshit. Could’ve been legit, or they could’ve just wanted to get out of class, or . . .’ A lift of Conway’s eyebrow. ‘They got a couple of painkillers and a nice lie-down, right by the shelf with the key.’

‘And they all said they didn’t touch it.’

‘Swore to Jesus. Like I said, I believed Emmeline. The rest . . .’ The eyebrow again. Sun through the leaves striped her cheeks like war paint. ‘The headmistress swore none of her girls would yada yada and the key had to have gone in the bin, but she changed the lock on the connecting door all the same. Better late than never.’ Conway stopped, pointed. ‘Look. See that over there?’