Wary eyes following us out of the staff room; wary eyes and cosy beef-stew smell, and just too soon, one step before we got out of earshot, a surge of low voices and shushing.

‘Thank Jesus,’ Conway said, ignoring. ‘That ought to narrow it down.’

I said, ‘She could’ve put it up herself.’

Conway took the stairs two at a time, back up towards McKenna’s office. ‘The teacher? Not unless she’s an idiot. Why get herself on the list? Throw the card up there someday when you’re not on duty, let someone else find it: no connection to you. She’s out, or as near as it gets.’

McKenna’s curly secretary had the list ready for us, all typed up and printed off, service with a smile. Orla Burgess, Gemma Harding, Joanne Heffernan, Alison Muldoon – given permission to spend first evening study period in art room (6.00–7.15 p.m.). Julia Harte, Holly Mackey, Rebecca O’Mara, Selena Wynne – given permission to spend second evening study period in art room (7.45–9.00 p.m.).

‘Huh,’ Conway said, taking the list back off me and leaning one thigh against the secretary’s desk to have another read. ‘Who woulda thought. I’ll need to talk to the eight of them, separately. And I want them all pulled out of class right now and supervised, nonstop, till I’m done.’ No point in letting them match up stories or move evidence, on the off-chance they hadn’t already. ‘I’ll have the art room, and a teacher to sit in with us. Whatshername, teaches French: Houlihan.’

The art room was free and Houlihan would be with us momentarily, as soon as someone was found to take over her class. McKenna had given orders: what the cops want, the cops get.

We didn’t need Houlihan. You want to interview an underage suspect, you need an appropriate adult present; you want to interview an underage witness, it’s your call. If you can skip the extra, then you do: there are things kids might tell you that they won’t say in front of Mammy, or in front of a teacher.

If you get in an appropriate adult, then it’s for reasons. I got the social worker in with Holly because I was on my own with a teenage girl, and because of her da. Conway wanted Houlihan for reasons.

Wanted the art room for reasons, too. ‘That,’ she said, at the door, jerking her chin at the Secret Place across the corridor. ‘When our girl walks past that, she’s gonna look.’

I said, ‘Unless she’s got serious self-control.’

‘If she did, she wouldn’t’ve put up that card to begin with.’

‘She had enough self-control to wait a year.’

‘Yeah. And now it’s cracking.’ Conway pushed open the art-room door.

The art room was cleaner-fresh, blackboard and long green tables washed bare. Gleaming sinks, two potter’s wheels. Easels, wooden frames stacked in a corner; smell of paint and clay. The back of the room was tall windows, looking out over the lawn and the grounds. I felt Conway remembering art class, one roll of paper and a handful of hairy paints.