I saw it now, the flushed skin and glittering eyes.

“Are you-?” I began.

“I’m not Changing. Not for a while. I know what that feels like now, and I’ve got a ways to go. Another day, at least. Hopefully longer.”

“I bet you’ll Change completely this time,” I said.

“Yeah, maybe.” His tone said he doubted it.

As we sat there, I snuck a look at him. At sixteen, Derek was more than a foot taller than me. Solidly built, too, with broad shoulders and muscles he usually kept hidden under baggy clothes, so he wouldn’t look as intimidating.

Since he’d started Changing, Mother Nature seemed to have cut him some slack. His skin was clearing up. His dark hair didn’t look greasy anymore. It still hung in his face-nothing emo, just like he hadn’t bothered to get it cut in a while. Lately, that would have been the last thing on his mind.

I tried to relax and enjoy the fog-laced view, but Derek fidgeted and squirmed, which was more distracting than if he’d just been his usual self and demanded to know what had happened.

“So there was this ghost,” I said finally. “He said he was a Volo half-demon. Telekinetic, but a stronger type than Dr. Davidoff. Probably the same kind Liz is. He lured me out here, locked the door, then started pelting me with stuff.”

Derek looked over sharply.

“I banished him.”

“Good, but you shouldn’t have followed him at all, Chloe.”

His tone was calm, reasonable, so un-Derek-like that I stared at him, the weird idea that this wasn’t Derek creeping through my head. Before I’d escaped the Edison Group laboratory, I’d met a demi-demon, chained there as a power source. She’d possessed someone but only a ghost. Could Derek be possessed?

“What?” Derek said as I stared.

“Are you okay?”

“Yeah, just…” He rubbed the back of his neck, wincing and rolling his shoulders. “Tired. Feeling off. Really off. Too much…” He struggled for the word. “Being here. Being safe. I’m still adjusting.”

That made sense. Derek’s werewolf protective streak had been in hyperdrive for days, keeping him awake and on guard. Having someone else to watch out for us now would be weird. Still, not blasting me for blithely following a random ghost onto a roof was so totally not Derek that I knew there was more to it.

When I asked what was bothering him, he muttered that it was nothing. I backed off and was about to explain more about the ghost when he blurted, “It’s Tori. I don’t like her story about how she got away.”

When the Edison Group had almost captured us last night, they’d nabbed Tori. Yet when they’d refocused their efforts on the biggest threat-Derek-they’d left the young witch with only a single guard. She’d locked him in a binding spell and escaped.

“You think they let her get away?”

“I’m not saying…It’s just…I don’t have any proof.”

And that’s what was making him uncomfortable, that his misgivings were based on nothing but a gut feeling. The math and science whiz really preferred dealing in facts.

“If you’re thinking she’s been a plant from the start, she hasn’t.” I lowered my voice. “Don’t tell her I told you this, okay? When she helped me escape, she only wanted to get away from the Edison Group and run back to her dad. So she called him. Instead he sent her mom-the woman we’d just escaped. Tori was hurt, really hurt. In shock even. She couldn’t have faked that.”

“I didn’t figure she was in on it from that far back.”

“Just that she cut a deal last night?”

“Yeah.”

“Would Tori turn us in for the promise of getting her old life back? It’s possible, and we should be careful, but I do buy her story. Unless her mom told them Tori was figuring out how to cast spells-which I doubt-then, as far as they know, she just has random outbursts of power. Her binding spell could have taken out a single guard. I’ve seen her use it. She doesn’t even need to say an incantation. It’s like, if she thinks it, she can do it.”

“No casting? No practicing?” He shook his head. “Don’t tell Simon that.”

“Don’t tell Simon what?” said a voice behind us.

We turned to see Simon step out of the doorway.

“That Tori doesn’t need to use incantations to cast,” Derek said.

“Seriously?” He swore. “You’re right. Don’t tell me.” He picked his way across the roof. “Better yet, don’t tell her that I need incantations and weeks of practice, and I still suck.”

“You were good with that knock-back spell last night,” I said.

He grinned. “Thanks. Now, do I dare ask what you guys are doing hiding out up here? Or is it going to make me jealous?”

Simon was smiling as he said it, but Derek glanced away with a gruff “Course not.”

“So you weren’t having another adventure?” Simon lowered himself on my other side, so close he brushed against me, hand resting on mine. “It sure looks like a good spot for one. Rooftop hideaway, old widow’s walk. That is what that is, huh? A widow’s walk?”

“Yeah. And it’s rotting, so stay off it,” Derek said.

“I did. So, adventure?”

“A small one,” I said.

“Oh, man. I always miss them. Okay, break it to me gently. What happened?”

I explained. As Simon listened, intent and concerned, he cast glances at his brother. Foster brother, I guess you’d say-one look at them and you knew they weren’t related by blood. Simon is fifteen, a half-year older than me, slender and athletic, with dark, almond-shaped eyes and spiked blond hair. When Derek was about five, he’d come to live with Simon and his dad. They were best friends and brothers, blood tie or not.

I told him as much as I’d told Derek so far. Then he looked from me to Derek.

“I must have been sound asleep if I missed all that shouting,” Simon said.

“What shouting?” Derek said.

“You mean that Chloe just told you that she followed a ghost onto a roof, and you didn’t blast her all the way to Canada?”

“He’s a little off this morning,” I said.

“More than a little, I’d say. Aren’t you going to ask her for the rest of the story? The part where she explains why she followed the ghost? Because I’m sure there was a reason.”

I smiled. “Thank you. There was. It was a teenage guy who knew about the Edison Group and the experiments.”

“What?” Derek’s head whipped around, the sound more growl than question.

“That’s why I followed him. There’s a dead kid here who might have been another subject, and if he died here…”

“Then that’s a problem,” Simon said.

I nodded. “My first thought, naturally, was ‘Oh my God, we’ve been led into a trap.’”

Simon shook his head. “Not Andrew. He’s one of the good guys. I’ve known him all my life.”

“But I haven’t, which is why I prodded the ghost, and it was clear he hadn’t recognized him. Andrew said this place was owned by the guy who started his group and was involved in the experiments. If there’s a link to this kid, I think we’ll find it there.”

“We can ask Andrew-” Simon began.

Derek cut him off. “We’ll find our own answers.”

Simon and Derek locked gazes. After a second, Simon grumbled something about making things difficult, but he didn’t argue. If Derek wanted to amuse himself playing detective, then fine. We’d be gone soon anyway, back to rescue those we’d left behind and take out the Edison Group…or so we hoped.