‘Other problem with our “client base”,’ she went on, ‘is that they’re getting smarter all the time. They know the hardware and software better than we do. We’re always trying to catch up. Here’s an example.’

She had nudged the mouse on her desk with her wrist. The computer screen, which had been blank, now showed a distorted image.

‘We call this a “swirl”,’ she explained. ‘Offenders send each other pictures, but only after they’ve encrypted them. Then we need to devise software to allow us to un-swirl them.’ With a click of the mouse, the photo began to resolve itself into an image of a man with his arm around an Asian boy. ‘You see?’ Inglis asked.

‘Yes,’ Fox said.

‘Plenty of other tricks, too. They’ve gotten so they can hide images behind other images. If you don’t know that’s the case, you might not bother stripping them out. We’ve seen hard drives hidden inside other hard drives…’

‘We’ve seen everything,’ Gilchrist stressed. Inglis looked across at her colleague.

‘Except we haven’t,’ she reminded him. ‘Every week there’s something new, something more revolting. All of it accessible twenty-four seven. You sit at your computer at home, surfing, maybe buying stuff or reading the gossip, and you’re about four clicks away from hell.’

‘Or heaven,’ Gilchrist interrupted, eyes fixed on his own screen. ‘It’s all a matter of taste. We’ve got stuff that would make the hairs on your scrotum stand on end.’

Fox knew that the Chop Shop considered itself a breed apart, different from the other cops at Fettes HQ: thicker-skinned, resilient, toughened by the job. A macho outfit, too. He wondered how hard Annie Inglis had worked in order to fit in.

‘You’ve got my attention,’ was all he said. Inglis was tapping at her screen with the tip of a ballpoint pen.

‘This guy here,’ she said, indicating the man with the Asian boy. ‘We know who he is. We know quite a lot about him.’