“This organism is part mouse, part amphibian. And part human.” He paused. “In a sense,” he said, “the enemy is us.” The room fell silent.

“Which of our genes is on that chromosome?” Jack asked softly. “What part of Chimera is human?”

“An interesting question,” said Petrovitch, nodding in approval.

“It deserves an interesting answer. You and Dr. Cutler will appreciate the significance of this list.” He typed on the keyboard.

On the screen appeared, Phospholipase A.

“My God,” murmured Todd Cutler. “These are all digestive enzymes.” The organism is primed to devour its host, thought Jack. It uses these enzymes to digest us from the inside, reducing our muscles and organs and connective tissue to little more than a foul soup.

“Jill Hewitt—she told us Hirai’s body had disintegrated,” said Randy Carpenter. “I thought she was hallucinating.”

Jack said suddenly, “This has got to be a bioengineered organism! Someone cooked this thing up in a lab. Took a bacteria or virus and grafted on genes from other species, to make it a more effective killing machine.”

“But which bacteria? Which virus?” said Petrovitch. “That’s the mystery here. Without more of the genome to examine, we can’t identify which species they started off with. USAMRIID refuses to show us the most important part of this organism’s chromosome. The part that identifies this killer.” He looked at Jack.

“You’re the only one here who’s actually seen the pathology at autopsy.”

“It was only a glimpse. They pushed me out of the room so fast I barely got a look. What I saw appeared to be some sort of cysts. The size of pearls, embedded in a blue-green matrix. They were in Mercer’s thorax and abdomen. In Hewitt’s cranium. I’ve never seen anything like it before.”

“Could they have been hydatid cysts?” asked Petrovitch.

“What’s that?” asked Woody.

“It’s an infection by the larval stage of a parasitic tapeworm called echinococcus. It causes cysts in the liver and lungs. For matter, in any organ.”

“You think this could be a parasite?”

Jack shook his head. “Hydatid cysts take a long time to grow. Years, not days. I don’t think this was a parasite.”

“Maybe they weren’t cysts at all,” said Todd. “Maybe they were spores. Fungus balls. Aspergillus or cryptococcus.”

Liz Gianni from Payloads cut in, “The crew reported a problem with fungal contamination. One of the experiments had to be destroyed because of overgrowth.”

“Which experiment?” asked Todd.

“I’d have to look it up. I remember it was one of the cell cultures.”

“But simple fungal contamination wouldn’t account for these deaths,” said Petrovitch. “Remember, there were fungi floating around Mir all the time, and no one died of it.” He looked at the computer screen. “This genome tells us we’re dealing with a new life-form. I agree with Jack. It must have been engineered.”

“So it’s bioterrorism,” said Woody Ellis. “Someone’s sabotaged our station. They must have sent it up in one of the payloads.” Liz Gianni vigorously shook her head. Aggressive and intense, she was a forceful presence at any meeting, and she spoke up now with absolute assurance.

“Every payload goes through safety review. There are hazard reports, three-phase analyses of all containment devices. Believe me, we would have nixed anything dangerous.”

“Assuming you knew it was dangerous,” said Ellis.

“Of course we’d know!”

“What if there was a breach in security?” said Jack. “Many of the experimental payloads arrive directly from the principal investigators—the scientists themselves. We don’t know what their security is like. We don’t know if they have a terrorist working lab. If they switched a bacterial culture at the last minute, we necessarily wouldn’t know?”

For the first time Liz looked uncertain. “It … it’s unlikely.”

“But it could happen.” Though she wouldn’t admit the possibility, dismay registered in her eyes. “We’ll grill every principal investigator,” she said.

“Every scientist who sent up an experiment. If they had a lapse in security, I’m fucking well gonna find out about it.”

She probably will, thought Jack. Like the other men in the room, he was a little afraid of Liz Gianni.

“There’s one question we haven’t asked yet,” said Gordon Obie, speaking up for the first time. As always, he’d been the Sphinx, listening without comment, silently processing information. “The question is why? Why would anyone sabotage the station? Is this someone with a grudge against us? A fanatic to technology?”

“The biological equivalent of the Unabomber,” said Todd Cutler.

“Then why not just release the organism at JSC and kill off our infrastructure? That would be easier, and far more logical.”

“You can’t apply logic to a fanatic,” Cutler pointed out.

“You can apply logic to everyone, including fanatics,” Gordon responded.

“As long as you know the framework in which they operate. And that’s why this bothers me. That’s why I wonder if we’re really dealing with sabotage.”

“What else would it be,” said Jack, “if not sabotage?”

“There is another possibility. It could be something just as frightening,” said Gordon, his troubled gaze lifting to Jack’s. “A mistake.”

Dr. Isaac Roman ran down the hall, his pager alarm squealing on his belt, dreading what he was about to face. He silenced the beeper and opened the door leading into the Level 4 isolation suite. He did not enter the patient’s room, but stood safely outside and stared the horror unfolding beyond the observation window.

There was blood splattered on the walls and pooling on the floor where Dr. Nathan Helsinger lay seizing. Two nurses and a physician in space suits were trying to stop him from injuring himself, but his spasms were so violent and so powerful they could not restrain him. His leg shot out and a nurse went sprawling, across the blood-slicked concrete floor.

Roman hit the intercom button. “Your suit! Is there a breach?” As she slowly rose to her feet, he could see her expression of terror. She looked down at her gloves, her sleeves, then at the juncture where the hose fed air into her suit. “No,” she said, and it was almost a sob of relief. “No breach.”

Blood splattered the window. Roman jerked back as bright droplets trickled down the glass. Helsinger was banging his head against the floor now, his spine relaxing, then hyperextending.

Opisthotonos. Roman had seen this bizarre posture only once before, in a victim of strychnine poisoning, the body curved backward like a bow strung under tension. Helsinger spasmed again, and his skull slammed backward against the concrete. Blood sprayed the faceplates of the two nurses.

“Back off!” Roman commanded through the intercom.

“He’s hurting himself!” said the physician.

“I don’t want anyone else exposed.”

“If we could get these seizures under control—”

“There’s nothing you can do to save him. I want you all to move away now. Before you get hurt.” Reluctantly the two nurses backed away. After a pause, so did the physician. They stood in silent helplessness as the scene of horror played out at their feet.

New convulsions sent Helsinger’s head whipping backward.

The scalp split open, like cloth ripping along a seam. The pool blood widened into a lake.

“Oh, God, look at his eyes!” one of the nurses cried.

The eyes were popping out, like two giant marbles straining to burst out of the sockets. Traumatic proptosis, thought Roman.

Helsinger’s eyeballs thrust forward by catastrophic intracranial pressure, the lids shoved apart, wide and staring.

The seizures continued, unrelenting, the head battering the floor.

Splinters of bone flew up and ticked against the window.

It was as though he were trying to crack open his own skull, to free whatever was trapped inside.