“Amanda.”

“Hi, Theo.”

While the smile remained, the door didn’t open any wider.

“To what do I owe the pleasure?” he said.

“I need help finding someone.”

Which was not, both of them knew, his job. But she had already tried the usual channels without success, and she figured Theo would recognize she was looking for a slightly different approach. Not outright illegal, but perhaps less conventional than the rule book strictly allowed for.

She also guessed he would be intrigued by the prospect of that. She was right. After a moment, the door opened properly.

“You should absolutely come in, then.”

She followed Theo into the room, closing the door behind her. Despite the unofficial title that officers had given it, the dark room was in reality anything but. Although it lacked natural light, it was so brightly illuminated, and the surfaces so impeccably clean and polished, that it reminded her of a laboratory.

And in a way, there really were things growing in here.

Amanda looked to one side. While most of the room was white and swept clear, the desks covered with neatly arranged monitors, one of the walls was darker and messier. A huge library of black hard drives was slotted into an elaborate shelving system, the cables that emerged between them carefully looped and tied but still creating a mass of bristly texture from which a multitude of tiny green and red LED lights blinked out like spider eyes. Each of the hard drives was carefully marked with a thin white label. Many of them, she knew, were the names of children. Not real, living ones, but the fake online personas that Theo and his team had created. There were equally fabricated adult identities. Other drives simply listed the names of internet forums. Some of those were notorious, but others, mercifully, were well beneath the radar of the general public.

The work Theo did in the dark room was simultaneously straightforward and horrifying. He and his team spent their days in the depths of the internet, dredging its silt. If there was anybody who could help her track down a ghost online, it was Detective Theo Rowan.

He was the only one in right now, and he led her over to a desk at the far end of the room.

“This is to do with the Price murder?” he said.

“Yes. The Unsolved and—”

“The Unknown. Yes, I remember. Tell me what you need.”

Amanda explained about the history of the case, and the user on the forum who had sent the photograph of what appeared to be Charlie Crabtree’s dream diary. Using Foster’s login, she had established that everybody registered on the site had a personal profile, but CC666’s had been left entirely blank. The site was hosted outside of the country, and the registration was private. She had contacted the anonymous owner through a link on the forum but had been met with silence. He or she seemed to have no desire to cooperate with the police. All of which meant that, so far, the only lead she had on the user known as CC666 was their words on a screen. It seemed like there was nowhere else to go.

Theo listened carefully, but halfway through he had already turned his attention to a monitor in front of him and begun typing quickly.

“And you think this person might be Crabtree?” he said.

“I don’t know,” Amanda said. “It doesn’t seem possible, but that’s what they seem to be implying in their messages. And given the way they encouraged Hick and Foster, I’d very much like to find out who they are. I just can’t see how.”

Theo finished typing.

“I can maybe get you their IP address.”

“You can?”

“Possibly. But you have to bear in mind that, even if I do, that might not be precise enough to identify them. IP addresses vary in their accuracy. I might not be able to pinpoint their exact house for you, but it might at least narrow it down to an area.”

“That would be good,” Amanda said. “How?”

Theo gestured across the room at his wall of hard drives.

“With a little help from my friends.”

Or, in other words: set a ghost to catch a ghost.

Theo explained he would use one of his cultivated false identities to set up an account at the forum, providing enough information on the profile for someone looking at it to establish that they appeared to be a living, breathing person with no connection to the police. He would then send a direct message to CC666, including a link designed to pique their curiosity. The link itself would look generic and innocent—the two of them chose a newspaper article—but it would run through a spoof page first that the person who clicked on it would never see. That page would record extensive data about the user: their internet connection; the details of their computer; a location of sorts. And since CC666 was the only person who would ever visit that link, they could be confident any information they got would belong to their man or woman.

Theo made it sound simple.

“Of course, it depends on CC666 taking the bait,” he said.

“Would you?”

He raised an eyebrow and laughed.

* * *

As Amanda took the elevator upstairs, she was still pondering the question she’d now been asked twice that day.

Did she think the user was Charlie Crabtree?

It was hard to imagine. Surely Crabtree must be dead by now. Or else someone would have found him. He had been fifteen years old at the time of the murder, and while what she had learned about the case had given her an idea of how cunning he had been and how carefully his plan had unfolded, it was difficult to believe he could have evaded capture all these years.

But not impossible.

The idea chilled her. If it really was him, then what was he doing?

What might his plan be now?

Back in her office, Amanda closed the blinds, switched off the light, and turned to her computer. She told herself to be sensible. Before she started thinking about ghosts, there were other avenues to explore.

I was there. DM me.

The police might not have found Charlie Crabtree twenty-five years ago, but the evidence against Billy Roberts had been overwhelming. Roberts had pled guilty to the murder. His lawyer had attempted to argue the boy was suffering from schizophrenia, but the diagnosis was contested by a second psychiatric examination, and the judge had ultimately rejected it. Implications of childhood abuse were taken into account, along with an acceptance that Crabtree had taken the lead in the crime. In the end, Roberts had been sentenced to twenty years in prison for the killing.

According to the online files she read through, he had responded well to the various initiatives and programs he had enrolled in over the course of his sentence. Evaluative reports repeatedly described him as thoughtful, repentant, and unlikely to present a further danger to society. He had been judged fit for release, and paroled over ten years ago.

Amanda leaned back in her chair.

Billy Roberts, a person who really had been there that day, was out there in the world somewhere right now.

The knowledge provoked mixed feelings. She had become familiar with the killing in Gritten, and the ferocity of what had been done there had lodged in her head. How could it not, she thought, when she had seen a reproduction of it with her own eyes in the quarry? The idea that one of the people responsible for such an atrocity was free in the community shook her a little.

But, of course, Billy Roberts had been little more than a child at the time of the murder. And she had to believe that people could change.