Altman looked at his chronometer. "We don't have much time," he said. "I don't know what creatures are still alive on the decks above or how long it'd take me to kill them. We'll have to go out the submarine bay."

"I didn't know there was still a submarine there," said Harmon.

"There isn't," said Altman.

"Then how-"

"We're going to swim," said Altman. "I'll flood the bay and open the doors. As soon as they open, swim out as quickly as you can and make for the surface. There's a rope. If you see it, follow it up. It'll lead you to the boat platform. I've left a boat moored there. I'll be right behind you."

Eyes wide, Harmon nodded.

They moved out. Altman took the lead, stayed on watch. Nothing. There must be more of the creatures in the facility, but he wasn't seeing them. He kept expecting them to crash their way out through a vent or to hear a door slide open behind him and find one suddenly looming over him, but no, nothing. That was almost worse than if there was something. It kept him tense, expectant, a coiled spring of energy that never could release itself.

By the time they reached the door of the submarine bay, there were two minutes left. The water was up to their knees in the corridor and when he tried to open the bay doors, they wouldn't respond. He threw the override and forced the doors open enough that they could slip through, the water from the hall pouring in along with them.

He tried to shut the door, but couldn't get it shut. As long as it wasn't shut, he wouldn't be able to flood the chamber. He called for Harmon to help him, but the man just stood there, motionless, staring down over the edge of the catwalk. Altman finally had to yell at him, threaten him. Together, with Altman working the manual controls and Harmon pushing the door along, they forced it shut.

"Swim higher in the chamber as the water rises," Altman said. "Keep your head above it until you get to the ceiling, then, once it starts to cover you, dive down and swim out the bottom. Got it?"

Harmon didn't respond.

Altman slapped him. "Got it?" he yelled.

Harmon nodded.

They began to flood the chamber. At first Harmon just stood there, watching the cold water rise, swirling up around his legs, and for a moment Altman just expected him to stand there, watching, not moving, and drown. But when the water reached his chest, he suddenly took a deep gasping breath and began to paddle.

"Remember," called Altman, floating now himself. "Up to the ceiling and then down and out the bottom and then all the way up to the surface. But not too fast."

He tried to keep his breathing slow, measured. The water all around him was swirling and foamy, and it was some effort to keep above it. He watched Harmon, but he seemed to be doing all right now. Twice he disappeared beneath the surface, but he reappeared again almost immediately.

And then Altman's head grazed the ceiling. He looked up at it and grabbed on to the grating there, holding still, breathing slowly in and out until the water covered his face.

He dived, stroking back to the controls, and opened the bay floor. Harmon was already down there, he saw, knocking against the metal of the floor, trying to get out. As soon as the floor split, he was through it and gone. Altman quickly followed.

The water was much darker than it had been earlier. He struck through it blindly, trying to go straight out, and then turned and started to rise too soon, striking the underside of the bay. He swam out farther and then made for the surface.

It wasn't as hard as going down, but it was difficult. The temptation was to go too quickly, which would have left him cramped and shivering and probably killed him. So, he went up slowly, all the while aware of the way his air was running out, his heart beating slower and slower. By the time he finally broke the surface, his lungs felt like they were on fire. There was a sliver of moon, just enough to see by. He looked around, saw the ghost of the boat platform, but no sign of Harmon. He spun his head around but didn't see him.

"Harmon!" he called as loud as he could.

He kicked up, trying to pull himself as far out of the water as he could. Even then, he wouldn't have seen it, if it hadn't been for the way a dip caught the platform and showed him the head floating on the other side.

He swam to the platform, climbed the ladder up onto it, and stumbled along the swaying platform to its far side. The facility now had started to settle strangely, listing in the water. There was the roar of water rushing into it, or maybe the roar was from something else, the whole structure creaking, too, as the change in buoyancy shifted its weight, putting pressure on girders and links.

"Harmon!" he called again.

But the man didn't hear him, perhaps couldn't hear him over the noise. Altman dived in, swam to him, touched him.

"Harmon," he said, "come on!"

He was confused and seemed dizzy, in a state of shock. Altman slapped him, pulled him toward the platform. He got him swimming again, though somewhat lethargically, and had to practically drag him up onto the platform once they arrived.

The platform was already listing, half submerged in water, being dragged down by the sinking dome. He pulled Harmon over to the boat and dumped him in, and fell in himself. Then the dome behind them creaked noticeably lower and the platform was underwater, the mooring rope between it and the boat stretched taut, the boat listing hard to one side, threatening to turn over. His fingers shaking, he picked at the knot, but the pressure had tightened it too much for him to loosen it. His eyes cast desperately around for a knife but he didn't see one. There was an anchor, though, and he grabbed it up and began striking the mooring with it as hard as he could, trying to break it free.

The boat tipped farther, very close to taking on water. "Get to the far side of the boat!" he cried at Harmon, but couldn't look around to see if he did. He kept hitting the mooring with hard, smashing blows.

Suddenly the boat bobbed back and threw him to the boards. It was only after scrambling up again with the anchor that he realized the mooring and rope were gone, that he had succeeded.

The boat began to swirl. There was a sucking sound as the facility began to go down now in earnest. He leapt into the driver's seat and started the craft, throwing the throttle down hard. The boat leapt forward, but it was heading wrong, directly toward the dome: he corrected it, but there was still something wrong. They were caught in a vortex, some sort of whirlpool that the facility was creating as it went down.

Instead of forcing the rudder against it, he turned and followed it, trying to edge carefully free. The last dome slipped all the way under and was gone. He felt the drag on the rudder but kept it steady, trying not to look to the side, trying not to panic. For an instant he felt the boat resisting him, threatening either to turn and plunge downward or to flip over, but then suddenly they were free.

He sped away, looking back over his shoulder. The inside of the compound, the little he could see of it through the waves, was flashing and sparking, the electrical systems and generator still in the process of shorting out. He had just a glimpse of it and then it was gone. He took the boat in a long curve then headed back toward Chicxulub.

He was just thinking he should check on Harmon when he realized that he was standing there behind him. He turned and was struck in the side of the head by the anchor, knocked out of his seat.

"You were lying, Altman," Harmon said. "The Marker didn't want to be sunk. You don't love the Marker, you hate it."

No, he tried to say, he tried to say, no no. But nothing came out.

He saw Harmon bend over him. He roughly took hold of Altman's hands, put them together, began to tie them.

"I thought you were my friend," said Harmon. "I thought you were a believer. But if you were really a believer, why don't you have one of these?" He touched the Marker pendant hanging from his neck. "I shouldn't have trusted you."

I saved you, Altman tried to say. Altman tried to say. I could have left you to die, but I saved your life. I could have left you to die, but I saved your life.

"Now I'm going to get some real help," said Harmon, and he stood and took the controls.

Altman lay there, eyes glazed. A warm fluid was puddling up against his cheek and his mouth. It was only when he tried to swallow that he realized it was blood. It took him another minute to realize it was his own.

Okay, he thought. he thought. I've been in worse situations. I've been in worse situations. He tried to move his hands, but couldn't feel them. It was as if his body had become disconnected from his head. He tried to move his hands, but couldn't feel them. It was as if his body had become disconnected from his head. I'll just rest a moment, I'll just rest a moment, he told himself. he told himself. I'll just lie here and then, in a moment, I'll wriggle free of these ropes. I'll just lie here and then, in a moment, I'll wriggle free of these ropes.

His vision started to go dim, and then slowly faded away. He listened to the sound of the engine, then that slowly left him, too. He lay there, feeling the movement of the boat through the waves. After a while, it seemed to come only from a distance. A while longer and even that was lost. He lay in the boat, seeing nothing, hearing nothing, feeling nothing. The whole world had dissolved around him. He tried as long as he could to focus on the taste of blood in his mouth. But soon he couldn't hold on to even that.

Epilogue And then it began again. It started first with a pinp.r.i.c.k of light in the darkness at a great distance. He watched it, trying to determine if it was getting closer or farther away, but was unable to say. He watched it a long time, or what felt like a long time, until it disappeared again.

Darkness. Plain and simple. But a sense, too, of a body. Of his his body, the limits of it. body, the limits of it.

I'm dead, he thought. he thought. This is h.e.l.l. This is h.e.l.l.

There was a long moment in which nothing happened. The pinp.r.i.c.k of light came back again. He did not notice it reappear exactly, just knew that it was there, and knew it had been there for a while. He watched it. This time it grew slowly larger. It was moving slowing toward him. Suddenly, it became excruciatingly bright.

Things began to take shape around it. A thin silvery casing from which the light itself came. Something pinkish nestled around it, which he began, slowly, to realize was a human hand.

"A little response," said a voice, flat, uninflected. "Up the dosage."

He felt something, a stinging somewhere on his body. Suddenly he could move the muscles on his face.

Where am I? he tried to ask, but what came out was a dim, inarticulate sound. he tried to ask, but what came out was a dim, inarticulate sound.

"There we are," said another voice. The light pulled back and he saw a face, half-hidden behind a surgical mask. Behind it were other faces, maybe a half dozen in all.

"Where am I?" he asked, and this time the words came out.

"You're alive," said the m.u.f.fled voice through the surgeon's mask. "That's all you need to know."

He tried to move his arm, found it strapped down. The other arm was strapped, too, his legs as well. He struggled against them, arched his back.

"There, there," said the voice. "You won't be able to break them. Just relax." The surgeon's mask turned to address someone behind him. "Go get Markoff," it said. "Tell him that Altman is awake."

He must have drifted off again. When he opened his eyes, there were three people over the bed, looking down at him: Krax, Markoff, and Stevens.

"Congratulations, Altman," said Krax. "You still seem to be alive."

When he opened his mouth and spoke, his voice was hoa.r.s.e, his throat sore. "You killed Ada," he said.

"No," said Krax. "Ada killed herself. She started hallucinating and then cut her own throat. She wasn't strong enough. She wasn't worthy."

"Worthy?" Altman asked.

"We need to have a little talk," said Markoff.

Altman narrowed his eyes. He watched him, warily.

"We've talked with your friend Harmon," said Krax. "He told us everything that happened."

"You sank the Marker," said Stevens. "Why would you do that?"

"It was dangerous," said Altman, his voice barely above a whisper.

"It's not dangerous," claimed Krax. "It's divine."

"You're crazy," said Altman.

"No, he's right," said Stevens. "I'm afraid that's the conclusion that all three of us have reached."

Altman turned his head slightly in Markoff's direction. It hurt to move it. "You don't believe this, do you? How can you believe it's divine now that you've seen what it's capable of?"

Markoff offered him a hard, glittering smile. "It created life," he said. "I saw that for myself, saw it take dead flesh and bring it back to life."

Maybe he doesn't actually believe, thought Altman. thought Altman. Or maybe he's pretending as a way of bending the others to his will. Just as I did with Harmon. Or maybe he's pretending as a way of bending the others to his will. Just as I did with Harmon.

"But what kind of life?" asked Altman. "It was monstruous."

"There must have been a glitch," said Stevens. "The Marker must have gotten damaged somehow. But as a principle, it's sound. All we have to do is fix it."

"Or if not fix it, make a new one," said Markoff.

"After all," said Stevens, "every indication is that when it was originally working, millennia ago, it established life on earth. Once we have one that's working properly, it will allow us to evolve beyond our mortal form. It will lead us into eternal life."

"No, it's not that. It's not that at all. You're wrong," whispered Altman. "It wasn't damaged; it was doing what it was meant to do. It meant to destroy us."

"Then why did it stop?" Stevens asked. "And why did it stop when you began to broadcast its own code back to it, showing that you'd figured out how to replicate it?"

"How do you know about that?"

"You don't think we left the facility without making sure that we could record everything that went on in it, do you?" said Krax. "We watched the whole thing. We have footage of everything."

But Altman just shook his head. "You're wrong," he said. "It'll destroy us."

"The Marker wants to help us," Stevens claimed. "Harmon has told us what you figured out: the Marker wants to be replicated. It was broken and must have known it was broken. It wants us to make it again so that it can help us. But we'll improve the technology, Altman. We'll make one that works and then make it even better." He leaned in closer. Altman could feel the man's breath on his face, could see in the man's eyes traces of fanaticism that belied his calm exterior. "There are sure to be other Marker s, somewhere, on other worlds," said Stevens. "They will lead us forward. In the meantime, we'll do our best to try to understand this one and duplicate it."

"You've done a lot to help with that," Markoff said.

"But this one is sunk," said Altman desperately.

"It was sunk before," said Markoff, "and we got it up. You know that as well as anyone. All you did was slow the inevitable down slightly, by a few weeks, a few months."

"You don't have the research," said Altman. "Everything must have been destroyed by the water and the pressure. You'll have to start over."

Krax shook his head. "Altman," he said. "You're so naive."

"Remember Harmon?" said Markoff. "What do you think Harmon was doing while he was in the Marker chamber? He was recording everything, making sure that none of the data would be lost. And then he carried it all away in his pocket. If you'd thought to check his pockets or simply left him to die, you might have set us back. But you didn't. You're far too trusting, Altman. We have everything."

"We also have all of Guthe's research," said Stevens. "We can learn from it what went wrong with the Marker and learn how to repair it. We ran our first experiments, synthesizing and reproducing the creature's DNA, while you were still unconscious. Hermetically sealed labs, a variety of fail-safes. We're being a great deal more careful about it than Guthe was, though most likely hallucinations were to blame for his rashness."

"And to be frank," said Krax, "watching you struggle past them taught us a great deal about how to control them. We wouldn't be nearly as far along without you."

"You're making a terrible mistake," whispered Altman. He was very tired. He was helpless, couldn't do anything. But maybe soon. All he had to do was regain his strength. Once he regained his strength, he'd do everything he could to stop them. "If you go ahead with this, it'll mean the end of humanity. Maybe not right away, but soon."

"That's what we're hoping for," said Stevens. "If we go ahead with this, we'll reach the next evolutionary stage. We won't be human; we'll be better than human."

"Good-bye, Altman," said Markoff. "You've been a worthy adversary. But this time you've lost."

Once the three of them had left, a doctor who had accompanied them to the door returned and whispered in the surgeon's ear. The surgeon nodded his head, and then filled and primed a hypodermic. He pushed it into Altman's arm. The world grew gray, slowly faded away.

2 When he woke up, he was still strapped down to a bed. He was alone in a small room, something very like a cell. He struggled against the straps, but they were firm.