“Suppose it’s true,” she said suddenly. “It’s hard to get my head around this nonsense—but suppose I concede that you’re right. That we have formed a—a sort of self-organizing collective here. Even that, in some way, after all these centuries, we have somehow diverged from the common human stock.”

“You’re waking up,” Peter said.

She snapped, “I don’t think you are in any position to patronize me. Let’s remember that you are the nutcase stuck in a hole in the wall with Semtex stuck up his arse.”

“Go on, Rosa,” I said quickly. “Suppose it’s true. Then what?”

“Then—” She raised her hands, lifted her head to the levels hidden above us, the great underground city. “If this is a new way, maybe it’s a better way. We have found a way to run a society, safely and healthily, with population densities orders of magnitude higher than anything else humans have hit on. What is the purpose of any human society? It is surely to provide a system in which as many people as possible can live out lives as long and healthy and happy and peaceful as possible. Wouldn’t it be better for humankind, and this whole crowded planet, if everyone lived peaceably together as they do here?”

“Little drone, you know too much,” he whispered.

She walked boldly up to the cleft. “Show your face, McLachlan.”

He switched on his torch. His face, eerily underlit, hovered in the shadows, his expression unreadable.

Rosa said, “Suppose you’re right. Suppose we are a new form—your word was Coalescents.”

“Yes.”

“Then shouldn’t you accept us for what we are?” She spread her arms. “What have you found, here in this cave under the Appian Way? Aren’t we Homo superior?”

He clicked off his torch; his face disappeared into the dark.

Rosa had an intense expression, almost a look of triumph.

I asked, “Did you believe all that?”

She glanced at me. “Not a word. I just want him out of there.” She was formidable indeed, I realized; I felt perversely proud.

Peter whispered again, from the dark. “George, she must have already figured some of this out for herself. Even if she didn’t want to face it. I just put it into words for her. She knew it all the time. Really, she’s too smart for the hive, for her own good.”

“But she’s listening,” I said quickly. “Maybe we should take it easy. Don’t do anything destructive. We’ll get the Order to open up, bring in the health professionals, the social workers . . .”

“There’s no time for that,” he said.

“Why not?”

“No time . . .” He fell silent, breathing heavily.

I tiptoed away. “I think he’s tiring,” I said to Rosa.

“Then,” she said, “before he triggers his dead man’s switch by falling asleep, I think you have a decision to make.”

“I have a decision?”