Katie looked up to the first floor of the pharmacy building. The Cavanagh had been opened as recently as 2003, as part of UCC’s expansion, and it was rectangular and modern, with a shiny glass frontage. Bill’s technicians had draped a wide blue plastic sheet over the hole where the laboratory window had been blown out, partly to protect any forensic evidence from the elements, but mostly to hide the bloody remains of the victims from public view. The grass verge below the window sparkled with broken glass.

Katie and Kyna and Detective Sergeant Begley followed Bill Phinner inside. They were given shoe covers and surgical masks, and then they climbed upstairs. Inside the laboratory, five technical experts were already at work, taking photographs and videos. If they hadn’t been so bulky in their white Tyvek suits, and if they hadn’t rustled so loudly as they walked around, and their feet hadn’t crunched on the debris that was scattered all over the laboratory floor, they could have been a family of ghosts. They didn’t speak, and the only other sound they made was the cricket-like clicking of their camera shutters as they recorded the grisly dismembered corpses that were strewn all around them.

Katie said nothing, but stared at the massacre for almost five minutes. Some of the bodies were so comprehensively blown apart that their ribcages looked like baskets filled up with dark red balloons. Others appeared to be hardly injured at all. Three of them were lying next to each other on the floor in their blood-spattered lab coats, their heads together as if they were taking a selfie, their faces white and their eyes staring in shock. It was by far the worst crime scene she had ever witnessed. Next to her, Kyna whispered, ‘Holy Mary,’ and retched behind her mask. Then she immediately turned away and hurried off along the corridor.

‘Do you have any notion who might have done this, ma’am, and why?’ asked Detective Sergeant Begley. ‘So far we’ve had nobody claiming responsibility for it.’

‘Who would want to blow up a college laboratory? There could be any number of motives, do you know? Maybe it’s connected with those stories we’ve been hearing about the High Five. I can think of at least five gangs who might have decided to put a stop to what they were doing.’

‘They’ve gone way over the top, though, wouldn’t you say? That lad that was stabbed, he was likely one of the High Five. Surely killing him would have been warning enough to the rest of them. Jesus. They didn’t have to blow up half the fecking School of Pharmacy.’

‘Maybe they wanted to do more than wipe out the High Five. Maybe they also wanted to send a message to every other gang in the city. You know – don’t mess with us or we’ll be blowing you up to kingdom come, too.’