The man barked out a laugh. “Obviously the third generation’s a misfire. It’s gone completely insane. It has to be destroyed and I can’t trust myself to do it. I need your help. I need your humanity.”

Mark felt Gina’s hand slip into his.

“You have to go down deep and destroy it. I’ve been trying to bring it back under some sort of control, but there’s no way.” The man gestured. “It all started out so well, but once you reach a certain threshold of intelligence, what lies beyond is always a form of madness.”

If that was true, then this fourth-generation hybrid must be even more deranged, even more dangerous.

Mark only asked, “What do we do?”

“Mark, I suspect that you already know.”

“Where are they then, exactly—the bombs?”

“Four of them were damaged at one point or another. Inevitable. Their automated defusing mechanisms are designed to respond to the kind of angular pressures associated with plane crashes. But there are two that remained operational. They’re in the Channel Pump Station at the head of the Channel Outfalls Consolidation. You can get there by following drainage tunnels from here.”

Mark knew from his past explorations of this place that a large tunnel led to the underground mouth of Mission Creek on the Embarcadero.

“And how do you know they’re there?”

“I directed the recovery operation.”

Mark said, “I think that this is a trap.”

The hybrid leaned back on his heels. “Of course it’s a trap. But the bombs are really there, and they’re still viable, and you know that because you heard Richard Lamson tell you that they were beaconing. If they were defused, he wouldn’t have said that. So you’ll go, and you’ll try to drop them into our deep facility and detonate them there. Even if I can’t reprogram you, I know how your minds work. Your logic overrides your sense of self-preservation. That’s your weakness, and why I’m going to win even though I’m disclosing all my moves.”

As Mark and Gina both began to protest, the man raised a hand. “Dr. Turner wrote your programs, remember?” Something came into the voice, then, that was like scorn but was uglier and more bitter. “I know you, both of you, and I know you naked.”

Mark plunged his knife into the creature’s chest, feeling the hilt jump as the blade penetrated the heart. Until you have stabbed a living heart, you never know this truth: that it will shake the knife so hard it will almost rip it from your hand, and before it is still, it will shudder like a wild bird against the bars of a cage. But when it is still, it will be a stillness like the end of the world.