DAY 6

11:22 P.M.

I landed on loose stones, and half stumbled, half slid down the slope toward the cave entrance. The thumping of the helicopter blades above us was loud. Mae was right beside me, but I could hardly see her in the thick dust. There were no Ricky figures anywhere in sight. We came to the cave entrance and stopped. Mae pulled out the thermite capsules. She gave me the magnesium fuses. She tossed me a plastic cigarette lighter. I thought, that's what we're using? Her face was already partly clouded behind the mask. Her eyes were hidden behind the night-vision goggles. She pointed to the interior of the cave. I nodded.

She tapped me on the shoulder, pointed to my goggles. I didn't understand, so she reached forward by my cheek and flicked a switch.

"-me now?" she said.

"Yes, I hear."

"Okay then, let's go."

We started into the cave. The green glow had vanished in the thick dust. We had only the infrared light mounted on top of our night-vision goggles. We saw no figures. We heard nothing but the thumping of the helicopter. But as we went deeper into the cave, the sound began to fade.

And as the sound faded, so did the wind.

Mae was focused. She said, "Bobby? Do you hear me?"

"Yes, I hear you."

"Get your ass in here."

"I'm trying to-"

"Don't try. Get in here, Bobby."

I shook my head. If I knew Bobby Lembeck, he was never coming into this pit. We rounded the bend, and saw nothing but suspended dust, the vague outlines of cave walls. The walls seemed smooth here, with no place to hide. Then from the gloom directly ahead I saw a Ricky figure emerge. He was expressionless, just walking toward us. Then another figure from the left, and another. The three formed a line. They marched toward us at a steady pace, their faces identical and expressionless.

"First lesson," Mae said, holding out the thermite cap.

"Let's hope they don't learn it," I said, and I lit the fuse. It sputtered white-hot sparks. She tossed the cap forward. It landed a few feet in front of the advancing group. They ignored it, staring forward at us.

Mae said, "It's a three count… two… one… and turn away." I twisted away, ducking my head under my arm just as a sphere of blinding white filled the tunnel. Even though my eyes were closed, the glare was so strong that I saw spots when I opened my eyes again. I turned back.

Mae was already moving forward. The dust in the air had a slightly darker tint. I saw no sign of the three figures.

"Did they run?"

"No. Vaporized," she said. She sounded pleased.

"New situations," I said. I was feeling encouraged. If the programming assumptions still held, the swarms would be weak when reacting to genuinely new situations. In time they would learn; in time they would evolve strategies to deal with the new conditions. But initially their response would be disorganized, chaotic. That was a weakness of distributed intelligence. It was powerful, and it was flexible, but it was slow to respond to unprecedented events. "We hope," Mae said.

We came to the gaping hole in the cave floor she had described. In the night goggles, I saw a sort of sloping ramp. Four or five figures were coming up toward us, and there seemed to be more behind. They all looked like Ricky, but many of them were not so well formed. And those in the rear were just swirling clouds. The thrumming sound was loud. "Second lesson." Mae held out a cap. It sizzled white when I lit it. She rolled it gently down the ramp. The figures hesitated when they saw it.

"Damn," I said, but then it was time to duck away, and shield my eyes from the explosive flash. Inside the confined space, there was a roar of expanding gas. I felt a burst of intense heat on my back. When I looked again, most of the swarms beneath us had vanished. But a few hung back, apparently undamaged.

They were learning.

Fast.

"Next lesson," Mae said, holding two caps this time. I lit both and she rolled one, and threw the second one deeper down the ramp. The explosions roared simultaneously, and a huge gust of hot air rolled upward past us. My shirt caught fire. Mae pounded it out with the flat of her hand, smacking me with rapid strokes.

When we looked again, there were no figures in sight, and no dark swarms.

We went down the ramp, heading deeper into the cave.

We had started with twenty thermite caps. We had sixteen left, and we had gone only a short distance down the ramp toward the large room at the bottom. Mae moved quickly now-I had to hurry to catch up with her-but her instincts were good. The few swarms that materialized before us all quickly backed away at our approach.

We were herding them into the lower room.

Mae said, "Bobby, where are you?"

The headset crackled. "-trying-get-"

"Bobby, come on, damn it."

But all the while we were moving deeper into the cave, and soon we heard only static. Down here, dust hung suspended in the air, diffusing the infrared beams. We could see clearly the walls and ground directly ahead of us, but beyond that, there was total blackness. The sense of darkness and isolation was frightening. I couldn't tell what was on either side of me unless I turned my head, sweeping my beam back and forth. I began to smell that rotten odor again, sharp and nauseating.

We were coming to level ground. Mae stayed calm; when a half-dozen swarms buzzed before us, she held out another cap for me to light. Before I could light the fuse, the swarms backed off. She advanced at once.

"Sort of like lion taming," she said.

"So far," I said.

I didn't know how long we could keep this up. The cave was large, much larger than I had imagined. Sixteen caps didn't seem like enough to get us through it. I wondered if Mae was worried, too. She didn't seem to be. But probably she wouldn't show it. Something was crunching underfoot. I looked down and saw the floor was carpeted with thousands of tiny, delicate yellow bones. Like bird bones. Except these were the bones of bats. Mae was right: they'd all been eaten.

In the upper corner of my night-vision image, a red light began to blink. It was some kind of warning, probably the battery. "Mae…" I began. Then the red light went out, as abruptly as it had begun.

"What?" she said. "What is it?"

"Never mind."

And then at last we came to the large central chamber-except there was no central chamber, at least, not anymore. Now the huge space was filled from floor to ceiling with an array of dark spheres, about two feet in diameter, and bristling with spiky protrusions. They looked like enormous sea urchins. They were stacked in large clusters. The arrangement was orderly. Mae said, "Is this what I think it is?" Her voice was calm, detached. Almost scholarly. "Yeah, I think so," I said. Unless I was wrong, these spiked clusters were an organic version of the fabrication plant that Xymos had built on the surface. "This is how they reproduce." I moved forward.

"I don't know if we should go in…" she said.

"We have to, Mae. Look at it: it's ordered."

"You think there's a center?"

"Maybe." And if there was, I wanted to drop thermite on it. I continued onward. Moving among the clusters was an eerie sensation. Thick mucuslike liquid dripped from the tips of the spikes. And the spheres seemed to be coated with a kind of thick gel that quivered, making the whole cluster seem to be moving, alive. I paused to look more closely. Then I saw that the surface of the spheres really was alive; crawling within the gel were masses of twisting black worms. "Jesus…"

"They were here before," she said calmly.

"What?"

"The worms. They were living in the layer of guano on the cave floor, when I came here before. They eat organic material and excrete high-content phosphorus compounds."