Yet he knew that was the least sensible course. After a few hours’ rest, they would all meet in HQ, their brains more alert, ready to begin this unprecedented investigation.

‘You should, you know,’ Emmet said, about to launch into a lecture about the need for sleep.

Tom smiled grimly and cut him off.

‘I know. I’ve delivered that advice often enough myself, old friend. You go, too. Let your team finish up here and come at it fresh tomorrow. We’re all going to need our wits about us for this one and the site will be secured for as long as we want.’

‘Do me a favour, Tom?’

‘What?’

‘Say a prayer with me.’

Tom blinked, surprised at the Tech chief’s request. He hadn’t pegged Emmet as a religious man. But standing there now, the bodies of the murdered women yards from their feet and the hour late, the inspector suddenly felt that praying was absolutely the appropriate reaction.

So he bowed his head and closed his eyes as Emmet intoned a Hail Mary, summoning the mother of Christ to help them find a killer. And when he’d finished, Tom, feeling like an utter hypocrite, silently made his own plea to a God he’d long stopped believing in. He prayed for the families of the murdered women and then he prayed that he’d never have to live through the grief that they were about to experience.

Willie drove the inspector home to his house on Blackhorse Avenue, a road that ran along one side of the sprawling Phoenix Park in west Dublin. They didn’t speak. Tom rested his head against the back of the seat. He felt like he’d been holding his breath all day and now, away from the scene, he was exhausted.

Willie sat erect in the driver’s seat, every now and again shaking his head and coughing to clear his throat. He’d chain-smoked as he hung around Glendalough, giving up his spare time to be on call in case Tom needed him. He too had been horrified as the news filtered out about the multiple bodies.

At home, Tom looked in on his daughter and granddaughter before going to bed.

Maria had taken Cáit in with her. The two faced each other on the pillow, one small head nose-to-nose with a bigger one, their features a mirror image bar their size. His daughter’s auburn hair fanned out on the pillow behind her. His granddaughter’s fairer hair was stuck to her head in sleep-damp curls.

The inspector felt his throat constrict as he looked at his sleeping beauties. They were safe and happy, oblivious to the evil that existed outside their dreams, unaware of the malevolence that he felt clung to the threads of his clothes after where he’d been.