They went silently back downstairs to the lobby. Katie found Kyna waiting for her, looking shivery and pale.

‘How are you going on, Kyna?’

‘A little less gawky, thanks, now that I’ve said goodbye to my breakfast. But I’ll be having the most desperate of nightmares when I go to bed tonight.’

‘Did you get the names of all the students who were in that class? And do you know which ones lost their lives and which ones didn’t?’

Kyna held up a sheet torn from a notepad. ‘I have them here. The principal just wrote them all down for me. Poor fellow could barely hold the pen.’

‘Okay, good. What we need to do now is to go around to all their relatives and friends and try to find out any reason at all why somebody might have been motivated to kill them. Either one of them, or some of them, or maybe the whole lot of them.’

‘Like you said, though, this is most likely the work of a drugs gang,’ put in Detective Sergeant Begley. ‘The Riordans, I’d place them top of the list, or maybe the O’Flynns. Or those headers from Lithuania, what do they call themselves, the Iron Wolves.’

‘It’s the most likely explanation, sure, that a drugs gang was responsible, but in the meantime we have to consider every possibility, no matter how unlikely. Maybe it was a mad jealous boyfriend. Or a student who was kicked off the pharmacy course for one reason or another, taking drugs maybe, and wanted his revenge. Or a Jehovah’s Witness or some other religious fanatic who thinks that medicine is tampering with the will of God.’

‘Right, then,’ said Kyna. ‘I’ll get Buckley and O’Sullivan on to it. And maybe Geoghegan too. I think he’s just about wrapped up that robbery at Michel Jewellers.’

Almost as soon as she had said that, her phone rang. She answered it and said, ‘Yes,’ and ‘yes,’ and, ‘thanks a million, yes, if you could text it to me.’ Then she said to Katie, ‘That was the secretary at St Catherine’s. I went to see her last night. It took her a bit of time but she’s been through the school records and identified that tall girl for me.’

‘That’s grand. Does she have a last known address for her, too?’

‘She’s sending it over. I can have Cushley find out if she’s still there, or if she’s moved away.’

‘Once you’ve located where she’s living, though, I want you to question her, Kyna, yourself. You’re the best we have when it comes to cajoling some babbling psychopath into explaining why he did what he did. Or she, in this case. Apart from that – well, maybe it’ll help you to take your mind off all that desperate mess we’ve seen upstairs.’