Tom darted a glance back up to Yuri, higher on the stairs. He saw that Yuri’s eyes had snapped open, a curious, razor-sharp intensity on his face. He wasn’t blinking, and as Tom twisted down the stairs, he mentally willed him, Close your eyes and pretend to zone out. What are you doing, man?

“I hope you realize, I know you’ve been trying to talk to someone outside the Spire,” Blackburn said, his voice echoing off the walls around them.

Tom stopped in his tracks. “I don’t know what you’re talking about.”

He saw movement out of the corner of his eye as he followed Blackburn down, and he realized with some disbelief that Yuri was quietly moving down the staircase, too, listening to them, just out of Blackburn’s line of sight.

What was he doing? Did he want to be caught?

“Don’t lie to me.” Blackburn whirled on him. “You have a friend in the Citadel. It makes me wonder about something: there’s no sign of a backdoor into our system, no evidence of external penetration of our server, yet there was a third neural processor interfacing with those drones, controlling those drones. If it wasn’t a neural processor outside the Spire, it was one inside our system, but if it was inside our system, I’d be able to trace it. I couldn’t.”

“So? What does that have to do with—”

“It means someone covered his tracks, Raines. He covered them thoroughly, and he did it within minutes of that assault on the system. There are only three people in the world capable of hiding their digital fingerprints so readily. One is my counterpart at the Sun Tzu Citadel—external to the Spire. One is Joseph Vengerov—again, external to the Spire. The third is me.”

“Maybe it was you,” Tom flung at him, keeping a careful eye on Yuri, too. “Maybe you have another personality you don’t know about. I mean, you were schizo—” His voice cut off when Blackburn abruptly seized him and hauled him around.

“Or maybe someone didn’t cover his tracks. Maybe he never left them. Maybe it was even a friend of yours who can move through a firewall undetected, purely by some quirk of his or her neural processor. If that was the case, it could be someone who entered our system and controlled those drones without leaving a shred of evidence. Just as he’s been tampering with my system without leaving evidence.” His eyes gleamed. “Is that who you’ve been contacting, Raines? Is it a ghost in the machine, someone from the Citadel who can penetrate my firewalls at will?”

No. Medusa wouldn’t do something like this. Not the breaches, not the sabotage of the drones. “I don’t think so.”