"I know," I said. The inside of the car was like an oven. Mae and I were both sweating. The swarm rushed toward us, and swirled over the front windshield, pulsating, shifting back and forth.

Over the headset, a panicked Ricky said, "Guys? Where are you? Guys?"

"We're in the cars."

"Which cars?"

"What fucking difference does it make?" Charley said. "We're in two of the fucking cars, Ricky."

The black swarm moved away from our sedan over to the Toyota. We watched as it slid from one window to another, trying to get in. Charley grinned at me through the glass. "It's not like the shed. These cars are airtight. So… fuck 'em."

"What about the air vents?" I said.

"I shut mine."

"But they aren't airtight, are they?"

"No," he said. "But you'd have to go under the hood to begin to get in. Or maybe through the trunk. And I'm betting this overbred buzzball can't figure that out." Inside our car, Mae was snapping closed the dashboard air ducts one after another. She opened the glove compartment, glanced inside, shut it again. I said, "You find any keys?"

She shook her head, no.

Over the headset, Ricky said, "Guys? You got more company."

I turned to see two additional swarms coming around the shed. They immediately swirled over our car, front and back. I felt like we were in a dust storm. I looked at Mae. She was sitting very still, stony-faced, just watching.

The two new clouds finished circling the car, then came to the front. One was positioned just outside Mae's passenger door window. It pulsed, glinting silver. The other was on the hood of the car, moving back and forth from Mae to me. From time to time, it would rush the windshield, and disperse itself over the glass. Then it would coalesce again, back away down the hood, and rush again.

Charley cackled gleefully. "Trying to get in. I told you: they can't do it." I wasn't so sure. I noticed that with each charge, the swarm would move farther back down the hood, taking a longer run. Soon it would back itself up to the front grill. And if it started inspecting the grill, it could find the opening to the air vents. And then it would be over. Mae was rummaging in the utility compartment between the seats. She came up with a roll of tape and a box of plastic sandwich baggies. She said, "Maybe we can tape the vents…" I shook my head. "There's no point," I said. "They're nanoparticles. They're small enough to pass right through a membrane."

"You mean they'd come through the plastic?"

"Or around, through small cracks. You can't seal it well enough to keep them out."

"Then we just sit here?"

"Basically, yes."

"And hope they don't figure it out."

I nodded. "That's right."

Over the headset, Bobby Lembeck said, "Wind's starting to pick up again. Six knots." It sounded like he was trying to be encouraging, but six knots wasn't anywhere near enough force. The swarms outside the windshield moved effortlessly around the car. Charley said, "Jack? I just lost my buzzball. Where is it?"

I looked over at Charley's car, and saw that the third swarm had slid down to the front tire well, where it was swirling in circles and moving in and out through the holes in the hubcap. "Checking your hubcaps, Charley," I said.

"Umm." He sounded unhappy, and with good reason. If the swarm started exploring the car thoroughly, it might stumble on a way in. He said, "I guess the question is, how big is their SO component, really?"

"That's right," I said.

Mae said, "In English?"

I explained. The swarms had no leader, and no central intelligence. Their intelligence was the sum of the individual particles. Those particles self-organized into a swarm, and their self-organizing tendency had unpredictable results. You really didn't know what they would do. The swarms might continue to be ineffective, as they were now. They might come upon the solution by chance. Or they might start searching in an organized way. But they hadn't done that so far.

My clothes were heavy, soaked in sweat. Sweat was dripping from my nose and chin. I wiped my forehead with the back of my arm. I looked at Mae. She was sweating, too. Ricky said, "Hey, Jack?"

"What."

"Julia called a while ago. She's checked out of the hospital and-"

"Not now, Ricky."

"She's coming out here tonight."

"We'll talk later, Ricky."

"I just thought you'd want to know."

"Jesus," Charley said, exploding. "Someone tell this asshole to shut up. We're busy!"

Bobby Lembeck said, "Eight knots of wind now. No, sorry… seven."

Charley said, "Jesus, the suspense is killing me. Where's my swarm now, Jack?"

"Under the car. I can't see what it's doing… No, wait… It's coming up behind you, Charley. Looks like it's checking out your taillights."

"Some kind of car freak," he said. "Well, it can check away."

I was looking over my shoulder at Charley's swarm when Mae said, "Jack. Look." The swarm outside her window on the passenger side had changed. It was almost entirely silver now, shimmering but pretty stable, and on this silver surface I saw Mae's head and shoulders reflected back. The reflection wasn't perfect, because her eyes and mouth were slightly blurred, but basically it was accurate.

I frowned. "It's a mirror…"

"No," she said. "It's not." She turned away from the window to look at me. Her image on the silver surface did not change. The face continued to stare into the car. Then, after a moment or two, the image shivered, dissolved and re-formed to show the back of her head. "What does that mean?" Mae said.

"I've got a pretty good idea, but-"

The swarm on the front hood was doing the same thing, except that its silver surface showed the two of us sitting side by side in the car, looking very frightened. Again, the image was somewhat blurred. And now it was clear to me that the swarm was not a literal mirror. The swarm itself was generating the image by the precise positioning of individual particles, which meant"Bad news," Charley said.

"I know," I said. "They're innovating."

"What do you figure, is it one of the presets?"

"Basically, yes. I assume it's imitation."

Mae shook her head, not understanding.

"The program presets certain strategies to help attain goals. The strategies model what real predators do. So one preset strategy is to freeze where you are and wait, to ambush. Another is to random-walk until you stumble on your prey, and then pursue. A third is to camouflage yourself by taking on some element of the environment, so you blend in. And a fourth is to mimic the prey's behavior-to imitate it."

She said, "You think this is imitation?"

"I think this is a form of imitation, yes."

"It's trying to make itself appear like us?"

"Yes."

"This is emergent behavior? It's evolved on its own?"

"Yes," I said.

"Bad news," Charley said mournfully. "Bad, bad news."

Sitting in the car, I started to get angry. Because what the mirror imaging meant to me was that I didn't know the real structure of the nanoparticles. I'd been told there was a piezo wafer that would reflect light. So it wasn't surprising that the swarm occasionally flashed silver in the sun. That didn't call for sophisticated orientation of the particles. In fact, you would expect that sort of silvery ripple as a random effect, just the way heavily trafficked highways will clog up and then flow freely again. The congestion was caused by random speed changes from one or two motorists, but the effect rippled down the entire highway. The same would be true of the swarms. A chance effect would pass like a wave down the swarm. And that's what we had seen.

But this mirroring behavior was something entirely different. The swarms were now producing images in color, and holding them fairly stable. Such complexity wasn't possible from the simple nanoparticle I'd been shown. I doubted you could generate a full spectrum from a silver layer. It was theoretically possible that the silver could be precisely tilted to produce prismatic colors, but that implied enormous sophistication of movement.