"The swarm swirled around the desert near the installation, like before. It came and went. For the next few days, we tried to gain control of it by radio, but we never could. And eventually-about a week after that-we found that none of the cars would start." He paused. "I went out there to have a look, and I found that all the onboard computers were dead. These days all automobiles have microprocessors built into them. They control everything from fuel injection to radios and door locks."

"But now the computers were not functioning?"

"Yeah. Actually, the processor chips themselves were fine. But the memory chips had eroded. They'd literally turned to dust."

I thought, Oh shit. I said, "Could you figure out why?"

"Sure. It wasn't any big mystery, Jack. The erosion had the characteristic signature of gamma assemblers. You know about that? No? Well, we have nine different assemblers involved in manufacturing. Each assembler has a different function. The gamma assemblers break down carbon material in silicate layers. They actually cut at the nano level-slicing out chunks of carbon substrate."

"So these assemblers cut the memory chips in the cars."

"Right, right, but…" David hesitated. He was acting as if I were missing the point. He tugged at his cuffs, fingered his collar. "The thing you have to keep in mind, Jack, is that these assemblers can work at room temperature. If anything, the desert heat's even better for them. Hotter is more efficient."

For a moment I didn't understand what he was talking about. What difference did it make about room temperature or desert heat? What did that have to do with memory chips in cars? And then suddenly, finally, the penny dropped.

"Holy shit," I said.

He nodded. "Yeah."

David was saying that a mixture of components had been vented into the desert, and that these components-which were designed to self-assemble in the fabrication structure-would also self-assemble in the outside world. Assembly could be carried out autonomously in the desert. And obviously, that's exactly what was happening.

I ticked the points off to make sure I had it right. "Basic assembly begins with the bacteria. They've been engineered to eat anything, even garbage, so they can find something in the desert to live off of."

"Right."

"Which means the bacteria multiply, and begin churning out molecules that self-combine, forming larger molecules. Pretty soon you have assemblers, and the assemblers begin to do the final work and turn out new microagents."

"Right, right."

"Which means that the swarms are reproducing."

"Yes. They are."

"And the individual agents have memory."

"Yes. A small amount."

"And they don't need much, that's the whole point of distributed intelligence. It's collective. So they have intelligence, and since they have memory, they can learn from experience."

"Yes."

"And the PREDPREY program means they can solve problems. And the program generates enough random elements to let them innovate."

"Right. Yes."

My head throbbed. I was seeing all the implications, now, and they weren't good. "So," I said, "what you're telling me is this swarm reproduces, is self-sustaining, learns from experience, has collective intelligence, and can innovate to solve problems."

"Yes."

"Which means for all practical purposes, it's alive."

"Yes." David nodded. "At least, it behaves as if it is alive. Functionally it's alive, Jack."

I said, "This is very fucking bad news."

Brooks said, "Tell me."

"I'd like to know," I said, "why this thing wasn't destroyed a long time ago."

David said nothing. He just smoothed his tie, and looked uncomfortable. "Because you realize," I said, "that you're talking about a mechanical plague. That's what you've got here. It's just like a bacterial plague, or a viral plague. Except it's mechanical organisms. You've got a fucking man-made plague."

He nodded. "Yes."

"That's evolving."

"Yes."

"And it's not limited by biological rates of evolution. It's probably evolving much faster."

He nodded. "It is evolving faster."

"How much faster, David?"

Brooks sighed. "Pretty damn fast. It'll be different this afternoon, when it comes back."

"Will it come back?"

"It always does."

"And why does it come back?" I said.

"It's trying to get inside."

"And why is that?"

David shifted uncomfortably. "We have only theories, Jack."

"Try me."

"One possibility is that it's a territorial thing. As you know, the original PREDPREY code includes a concept of a range, of a territory in which the predators will roam. And within that core range, it defines a sort of home base, which the swarm may consider to be the inside of this facility."

I said, "You believe that?"

"Not really, no." He hesitated. "Actually," he said, "most of us think that it comes back looking for your wife, Jack. It's looking for Julia."

That was how, with a splitting headache, I found myself on the phone to the hospital in San Jose. "Julia Forman, please." I spelled the name for the operator. "She's in the ICU," the operator said.

"Yes, that's right."

"I'm sorry but direct calls are not allowed."

"Then the nursing station."

"Thank you, please hold."

I waited. No one was answering the phone. I called back, went through the operator again, and finally got through to the ICU nursing station. The nurse told me Julia was in X-ray and didn't know when she would be back. I said Julia was supposed to be back by now. The nurse said rather testily that she was looking at Julia's bed right now, and she could assure me Julia wasn't in it.

I said I'd call back.

I shut the phone and turned to David. "What was Julia doing in all this?"

"Helping us, Jack."

"I'm sure. But how, exactly?"

"In the beginning, she was trying to coax it back," he said. "We needed the swarm close to the building to take control again by radio. So Julia helped us keep it close."

"How?"

"Well, she entertained it."

"She what?"

"I guess you'd call it that. It was very quickly obvious that the swarm had rudimentary intelligence. It was Julia's idea to treat it like a child. She went outside with bright blocks, toys. Things a kid would like. And the swarm seemed to be responding to her. She was very excited about it."

"The swarm was safe to be around at that time?"

"Yes, completely safe. It was just a particle cloud." David shrugged. "Anyway, after the first day or so, she decided to go a step further and formally test it. You know, test it like a child psychologist."

"You mean, teach it," I said.

"No. Her idea was to test it."

"David," I said. "That swarm's a distributed intelligence. It's a goddamn net. It'll learn from whatever you do. Testing is teaching. What exactly was she doing with it?"

"Just, you know, sort of games. She'd lay out three colored blocks on the ground, two blue and one yellow, see if it would choose the yellow. Then with squares and triangles. Stuff like that."

"But David," I said. "You all knew this was a runaway, evolving outside the laboratory. Didn't anybody think to just go out and destroy it?"

"Sure. We all wanted to. Julia wouldn't allow it."

"Why?"

"She wanted it kept alive."

"And nobody argued with her?"

"She's a vice president of the company, Jack. She kept saying the swarm was a lucky accident, that we had stumbled onto something really big, that it could eventually save the company and we mustn't destroy it. She was, I don't know, she was really taken with it. I mean, she was proud of it. Like it was her invention. All she wanted to do was 'rein it in.' Her words."