In retrospect, I was right about one thing: it was vitally important to know how the rabbit had died. Of course I know the reason now. I also know why the rabbit was attacked. But that first day at the laboratory, I didn't have the faintest notion of what had happened. And I could never have guessed the truth.

None of us could have, at that point.

Not even Ricky.

Not even Julia.

It was ten minutes after the swarms had gone and we were all standing in the storage room. The whole group had gathered there, tense and anxious. They watched me as I clipped a radio transmitter to my belt, and pulled a headset over my head. The headset included a video camera, mounted by my left ear. It took a while to get the video transmitter working right. Ricky said, "You're really going out there?"

"I am," I said. "I want to know what happened to that rabbit." I turned to the others. "Who's coming with me?"

Nobody moved. Bobby Lembeck stared at the floor, hands in his pockets. David Brooks blinked rapidly, and looked away. Ricky was inspecting his fingernails. I caught Rosie Castro's eye. She shook her head. "No fucking way, Jack."

"Why not, Rosie?"

"You saw it yourself. They're hunting."

"Are they?"

"Sure as hell looked like it."

"Rosie," I said, "I trained you better than this. How can the swarms be hunting?"

"We all saw it." She stuck her chin out stubbornly. "All three of the swarms, hunting, coordinated."

"But how?" I said.

Now she frowned, looking confused. "What are you asking? There's no mystery. The agents can communicate. They can each generate an electrical signal."

"Right," I said. "How big a signal?"

"Well…" She shrugged.

"How big, Rosie? It can't be much, the agent is only a hundredth of the thickness of a human hair. Can't be generating much of a signal, right?"

"True…"

"And electromagnetic radiation decays according to the square of the radius, right?" Every school kid learned that fact in high school physics. As you moved away from the electromagnetic source, the strength faded fast-very fast.

And what that meant was the individual agents could only communicate with their immediate neighbors, with agents very close to them. Not to other swarms twenty or thirty yards away. Rosie's frown deepened. The whole group was frowning now, looking at each other uneasily.

David Brooks coughed. "Then what did we see, Jack?"

"You saw an illusion," I said firmly. "You saw three swarms acting independently, and you thought they were coordinated. But they're not. And I'm pretty certain that other things you believe about these swarms aren't true, either." …

There was a lot I didn't understand about the swarms-and a lot I didn't believe. I didn't believe, for example, that the swarms were reproducing. I thought Ricky and the others must be pretty unnerved even to imagine it. After all, the fifty pounds of material they'd exhausted into the environment could easily account for the three swarms I had seen-and dozens more besides. (I was guessing that each swarm consisted of three pounds of nanoparticles. That was roughly the weight of a large bee swarm.) As for the fact that these swarms showed purposeful behavior, that was not in the least troubling; it was the intended result of low-level programming. And I didn't believe the swarms were coordinated. It simply wasn't possible, because the fields were too weak. Nor did I believe the swarms had the adaptive powers that Ricky attributed to them. I'd seen too many demos of robots carrying out some task-like cooperating to push a box around the room-which was interpreted by observers as intelligent behavior, when in fact the robots were stupid, minimally programmed, and cooperating by accident. A lot of behavior looked smarter than it was. (As Charley Davenport used to say, "Ricky should thank God for that.") And finally, I didn't really believe that the swarms were dangerous. I didn't think that a three-pound cloud of nanoparticles could represent much of a threat to anything, not even a rabbit. I wasn't at all sure it had been killed. I seemed to recall that rabbits were nervous creatures, prone to die of fright. Or the pursuing particles might have swarmed in through the nose and mouth, blocking the respiratory passages and choking the animal to death. If so, the death was accidental, not purposeful. Accidental death made more sense to me. In short, I thought that Ricky and the others had consistently misinterpreted what they saw. They'd spooked themselves.

On the other hand, I had to admit that several unanswered questions nagged at me. The first, and most obvious, was why the swarm had escaped their control. The original camera swarm was designed to be controlled by an RF transmitter beaming toward it. Now apparently the swarm ignored transmitted radio commands, and I didn't understand why. I suspected an error in manufacturing. The particles had probably been made incorrectly. Second was the question of the swarm's longevity. The individual particles were extremely small, subject to damage from cosmic rays, photochemical decay, dehydration of their protein chains, and other environmental factors. In the harsh desert, all the swarms should have shriveled up and died of "old age" many days ago. But they hadn't. Why not? Third, there was the problem of the swarm's apparent goal. According to Ricky, the swarms kept coming back to the main building. Ricky believed they were trying to get inside. But that didn't seem to be a reasonable agent goal, and I wanted to look at the program code to see what was causing it. Frankly, I suspected a bug in the code. And finally, I wanted to know why they had pursued the rabbit. Because PREDPREY didn't program units to become literal predators. It merely used a predator model to keep the agents focused and goal-oriented. Somehow, that had changed, and the swarms now appeared to be actually hunting.

That, too, was probably a bug in the code.

To my mind, all these uncertainties came down to a single, central question-how had the rabbit died? I didn't think it had been killed. I suspected the rabbit's death was accidental, not purposeful.

But we needed to find out.

I adjusted my portable radio headset, with the sunglasses and the video camera mounted by the left eye. I picked up the plastic bag for the rabbit's body and turned to the others. "Anybody coming with me?"

There was an uncomfortable silence.

Ricky said, "What's the bag for?"

"To bring the rabbit back in."

"No fucking way," Ricky said. "You want to go out there, that's your business. But you're not bringing that rabbit back here."

"You've got to be kidding," I said.

"I'm not. We run a level-six clean environment here, Jack. That rabbit's filthy. Can't come in."

"All right, then, we can store it in Mae's lab and-"

"No way, Jack. Sorry. It's not coming through the first airlock." I looked at the others. They were all nodding their heads in agreement.

"All right, then. I'll examine it out there."

"You're really going to go out?"

"Why not?" I looked at them, one after another. "I have to tell you guys, I think you've all got your knickers in a twist. The cloud's not dangerous. And yes, I'm going out." I turned to Mae. "Do you have a dissection kit of some kind that-"

"I'll come with you," she said quietly.

"Okay. Thanks." I was surprised that Mae was the first to come around to my way of seeing things. But as a field biologist, she was probably better than the others at assessing real-world risk. In any case, her decision seemed to break some tension in the room; the others visibly relaxed. Mae went off to get the dissecting tools and some lab equipment. That was when the phone rang. Vince answered it, and turned to me. "You know somebody named Dr. Ellen Forman?"