Exactly twenty-seven minutes and thirty seconds later, just as Dr Griffin was explaining how the drug prednisolone could ease inflammation but possibly cause peptic ulcers, the box blew up.

The blast devastated the laboratory, blowing out all the windows into College Road, and shattering every single bottle and test tube and retort flask into a blizzard of sharp glass shards. Cormac, who had been sitting closest to the box, was shredded into a long, ragged string of red muscles, tangled with bones. Next to him, Lorraine’s head was knocked off by the blast and sent spinning out of the window with her dark hair whirling, while her body burst open and her bloody lungs flapped up as if they were wings.

In the row in front of them, Eoin’s head was torn off, too, leaving him with a bony stalk of vertebrae for a neck. Kevin was standing with his back to the box, stretching. Both of his arms were ripped off and whirled away in different directions, as if they were frantically signalling, while his stomach exploded out of his lab coat and his intestines unravelled like a speeded-up film, piling over the window sill in pale slippery loops.

Dr Griffin had just turned away from the whiteboard to face his students when the box was detonated, and he was caught in the hailstorm of thousands of sharp glass fragments. His entire face was instantly flayed into thin scarlet ribbons of skin, and his Donegal tweed jacket was shredded into shoddy. He was thrown backwards and sideways and disappeared under his desk.

Half of the laboratory ceiling collapsed at an angle. Pipes burst and electricity cables were torn apart, so that water began to shower down over the bodies and the wreckage, and sparks jumped and crackled through the indoor rain. In all, Dr Griffin and eleven students had been killed, and three students devastatingly injured. One girl had survived because she had bent down to pick up her pen when she had dropped it, but her right hip and most of her right buttock had been blasted away.

The School of Pharmacy was over two kilometres away from the city centre, but the bang was so loud that it had been heard by shoppers on St Patrick’s Street. They stopped, and looked up, and many of them thought that a plane could have crashed, up at the airport.

Katie had just opened her office window to let in some fresh air, and she heard it, too. She had heard bombs going off before, and she knew at once what it was. She rang down to Superintendent Pearse and said, ‘Michael – did you hear that?’

‘Did I hear what?’

‘It sounded like a bomb going off. I can’t be sure what direction it came from. To the west, I’d say.’

‘Sorry, no. I had on my earphones. I was listening to last night’s interview with Minister Flanagan.’