I watched Stu clicking on a couple of the web pages for ages.

“Have you found anything?” I asked eventually.

Stu clicked another page, then stopped. “No. Time to go into the darknet.”

That was kind of exciting, because Dad talks about the darknet a lot, how it’s this underworld of the internet, where everything’s secret and nothing’s traceable. How you can’t get in unless you know the special routes and passwords.

“What’s your access point?” I asked Stu, trying to sound like I knew what I was talking about.

“Well, there’s a website—” He stopped, and looked at me with narrowed eyes. “Nice try, but I know your dad wouldn’t want me telling you that.” He waved his hand, shooing me back.

“Oh come on!”

Stu folded his arms, refusing to do anything until I was right across the other side of the room. “I’m sorry, Gray, but the darknet isn’t for mucking about in. It’s not funny cats in there. In the darknet, everything’s for sale, even humans.” He looked at me. “And the people aren’t nice; they won’t care that you’re a kid.” He paused. “Or they might care too much.”

“So why are you going in then?” I muttered. “If it’s so bad and full of psychos?”

Stu grinned. “Because the main thing on sale in the darknet is information. Stolen credit card details, stuff hacked from mobile phones or scavenged out of people’s bins. Identities, bank accounts, government secrets. You name it, you can buy it, if you’ve got enough cash. Not that I would, of course, since I’m not a criminal.” He sighed. “Most stuff is out of my price range anyway, but I should be able to afford an identity check on this Dr Harcourt.”

I had to spend ten slow minutes in the corner, before Stu whistled to himself.

“Interesting.”

“What?” I took a step nearer, trying to see, but Stu closed off the web page, leaving nothing but his screensaver. Which was a picture of himself Photoshopped into Doctor Who.

“The prices on her are astronomical – you’d need to be a millionaire to afford them.”

I sagged, feeling a bit hopeless. “So that’s a dead end?”

Stu shook his head. “Actually, it tells me a lot. If the prices are that high, it means someone is paying to stop the information being sold.” He smiled. “And I’ve got other ways of finding things out.”

He shooed me away and carried on tapping. After a while he leaned back, put all his fingertips into his hair and scratched thoughtfully. Little flecks of white appeared on his shoulders.

“Nothing, nothing, nothing.” Scratch, scratch. “Makes me think maybe she isn’t a real person.”

“What? Like a robot, or a zombie takeover?”

Stu glanced at me. “Fake persona. A cover story. Good enough to fool your average web search, but here in the darknet…” He hummed the Star Wars theme tune to himself. “Let’s try another way. Tell me the names of your classmates, the ones who went into the quarry site with you.”

I went through everyone I could remember and he tapped away, but it was obviously getting nowhere because he got grumpy.

“Useless. Nothing and nothing.” He glared at me. “Is that all of them? What about that girl? Daughter of Gil’s girlfriend. Isis something.”

“Dunbar,” I said. “But she wasn’t even in our group, she didn’t go into…” Stu was tapping as I talked, and then he burst out laughing.

“What?”

Stu shook his head, like it was a really good joke. “If I put her name in, I just get stuff on Mr Dunbar.”

“Her dad’s in the darknet?”

“No! It’s a coincidence. She’s just some girl you know, and Mr Dunbar is, well, he’s a Mr Big. Supposed to be high up in the Organisation – there’s stories about him you wouldn’t believe, but never any evidence of anything. He’s very good at covering his tracks. My own theory is it’s a code name, not a person. A cover for lots of different agents.” He sucked through his teeth. “Nothing to do with this though…” He stopped, clicked back through a few pages. “Or… oh! Why didn’t I think of it before?”

“Think of what?”

“Who has the money to keep information about Dr Harcourt out of the darknet?”

I shook my head, I mean, how would I know?

“The Organisation!” He got up and hurried into the hallway, grabbing my coat. “Let’s go!”

“Go where?” I followed him. “I thought we were waiting for Dad?”

Stu shook his head. “We need to be at the quarry, gathering evidence! If this is to do with the Organisation, I might be able to find something out, get a lead on them!” He was practically hopping with excitement, probably imagining himself getting some kind of super-freak medal for being the one to unmask the Organisation, or whatever.

But going to the quarry; I thought my heart would stop. “No, no way! That’s where all this started, and you want me to go back there?”

Stu shoved my coat at me. “Don’t you want to find out what’s wrong with you? How can you unless you’re willing to take a few risks?”

“You don’t even know it is the Organisation!”

Stu made a noise. “Pfft! I know their fingerprints when I see them!”

“I don’t want to!”

Stu shook his head. “You’re my canary, literally in the mine. I need to see if you drop inside your cage.”

“Oh, great.”

He was practically dragging me out of the door. “Please?” he wheedled. “They’re only hallucinations. They can’t actually hurt you, can they?”

I stared out at Stu’s garden, and the street beyond. It looked so ordinary, but I knew that as soon as I took a step out there they’d know, somehow. The ghosts, or zombies, or whatever they were. And I didn’t believe Stu about them not being able to hurt me, or that they were only hallucinations. But if I didn’t face them, would my life be like this forever? Too scared to go outside?

I knew I couldn’t do it by myself. Stu was no use, he was already off on his own thing, chasing secret societies and conspiracies and Mr Dunbar… Oh.

That’s you, isn’t it?

I have gone by that name.

But Isis said her dad works on cruise ships and that’s why he’s never around… That’s a cover story, isn’t it?

Your suggestion, not mine.

How could you just leave her? Don’t you care about your own daughter? Or, were you sent off on a mission? Is Isis being psychic something to do with you? Is that why you married Cally?

I have revealed some things to you because you’ll forget them anyway. But certain information, like the answers to these questions, I will not give.

You’re only a boy, Gray, not an agent.