But necrotizing streptococcus has its own agenda, its own timetable for killing. Just like Chimera.

He drew in a breath of air and wondered how many viruses, how many bacteria, how many fungi, had just swirled into his lungs. And which of those might kill him.

August 15

“I say fuck’em,” said Luther. The air-to-ground comm was off, conversation unmonitored by Mission Control. “Let’s get back on the CRV, flip the switches, and go. They can’t make us turn and come back.” Once they left the station, they couldn’t turn around. The CRV was essentially a glider with drag chutes. After separation from ISS, it could travel a maximum of four revolutions around the earth before it was forced to deorbit and land.

“We’ve been advised to sit tight,” said Griggs. “That’s exactly what we’re going to do.”

“Follow stupid shit orders? Nicolai’s going to die on us if we don’t get him home!”

Griggs looked at Emma. “Opinion, Watson?” For the last twenty-four hours, Emma had been hovering by her patient, monitoring Nicolai’s condition. They could all see for themselves that he was in critical condition. Tied down to the medical restraint board, he twitched and trembled, his limbs flailing out with such violence Emma was afraid he’d snap his bones. He looked like a boxer who had been pummeled mercilessly in the ring. Subcutaneous emphysema had bloated the soft tissues Of his face, swelling his eyelids shut. Through the narrow slits, sclerae were a brilliant, demonic red.

She didn’t know how much Nicolai could hear and understand, so she didn’t dare say aloud what she was thinking. She motioned her crewmates out of the Russian service module.

They met in the hab, where Nicolai could not hear them, and where they could safely remove their goggles and masks.

“Houston needs to clear our evac now,” she said, “or we’re going to lose him.”

“They’re aware of the situation,” said Griggs. “They can’t authorize an evac until the White House clears it.”

“So we’re just gonna hang around up here and watch each other get sick?” said Luther. “What if we just got in the CRV and left? What’re they gonna do, shoot us down?”

Diana said quietly, “They could.” The truth of what she’d just said made them all fall silent. Every astronaut who had ever climbed aboard the shuttle and sweated through a countdown knew that sitting in a bunker at KSC was a team of Air Force officers whose only job was to blow up the shuttle, incinerating the crew. Should the steering system go awry during launch, should the shuttle veer disastrously toward a crowded area, it was the duty of these range-safety officers to press the destruct buttons. They had met every member of the shuttle’s crew. They had probably seen photographs of the astronauts’ families. They knew exactly who they would be killing. It was a responsibility, yet no one doubted those Air Force officers would carry it out.

Just as they would almost certainly destroy the CRV if so ordered. When faced with the specter of a new and lethal epidemic, the lives of five astronauts would seem trivial.

Luther said, “I’m willing to bet they’ll let us land safely. Why wouldn’t they? Four of us are still healthy. We haven’t caught anything.”

“But we’ve already been exposed,” said Diana. “We’ve breathe the same air, shared the same quarters. Luther, you and Nicolai slept together in that air lock.”

“I feel perfectly fine.”

“So do I. So do Griggs and Watson. But if this is an infection, we may already be in the incubation stages.”

“That’s why we have to follow orders,” said Griggs. “We stay right where we are.” Luther turned to Emma. “Do you go along with this martyr shit?”

“No,” she said. “I don’t.” Griggs looked at her in surprise. “Watson?”

“I’m not thinking about myself,” said Emma. “I’m thinking about my patient. Nicolai can’t talk, so I have to do it for him.

“I want him in a hospital, Griggs.”

“You heard what Houston said.”

“What I heard was a lot of confusion. Evac orders being given, then belayed. First they tell us it’s Marburg virus. Then they it’s not a virus at all, but some new organism cooked up by bioterrorists. I don’t know what the hell’s going on down there. All I know is, my patient is…” She abruptly lowered her voice.

“He’s dying,” she said softly. “My primary responsibility is to keep him alive.”

“And my responsibility is to act as commander of this station,” said Griggs. “I have to believe that Houston is calling the shots best they can. They wouldn’t put us in this danger unless the situation was truly grave.” Emma could not disagree. Mission Control was manned by people she knew, people she trusted. And Jack is there, she thought. There was no human being she trusted more than him.

“Looks like we have data being uplinked,” said Diana, glancing at the computer. “It’s for Watson.” Emma glided across the module to read the message glowing on the screen. It was from NASA Life Sciences.

Emma called up the attached file.

It took her a moment to mentally process the nucleotide sequence that flowed across the screen. A few minutes more to actually believe the conclusions.

Genes from three different species were on one chromosome.

Leopard frog. Mouse. And human.

“What is this organism?” asked Diana.

Emma said softly, “A new life-form.” It was a Frankenstein’s monster. An abomination of nature. She suddenly focused on the word “mouse,” and she thought, The mice. They were the first to get sick. Over the past week and a they had continued to die. The last time she had checked the cage, only one mouse, a female, was still alive.

She left the hab and headed deeper into the powered-down half of the station.

The U.S. Lab was deep in gloom. She floated across the semidarkness to the animal holding rack. Had the mice been the original carriers for this organism, the vessels in which the been brought aboard ISS? Or were they just the accidental victims, infected through exposure to something else aboard the station?

And was the last mouse alive?

She opened the rack drawer and peered into the cage at the lone resident.

Her heart sank. The mouse was dead.

She had come to think of this female with the chewed-up ear as a fighter, the scrappy survivor who, through sheer orneriness, outlasted its cage mates. Now Emma felt an unexpected pang of grief as she gazed at the lifeless body floating at the far end of cage. Its abdomen already looked bloated. The corpse would have to be removed immediately and discarded with the contaminated trash.

She interfaced the cage to the glove box, inserted her hands into the gloves, and reached in to grab the mouse. The instant fingers closed over it, the corpse suddenly scrabbled to life. Se gave a scream of surprise and released it.

The mouse flipped over and glared at her, whiskers twitching in irritation.

Emma gave a startled laugh. “So you’re not dead after all,” she murmured.

“Watson!” She turned toward the intercom, which had just spat out her name. “I’m in the lab.”

“Get in here! The RSM. Nicolai’s seizing!” She flew out of the lab, caroming off walls in the gloom as she shot toward the Russian end. The first thing she saw as she popped into the RSM were the faces of her crewmates, their horror evident even through their goggles. Then they moved aside and she saw Nicolai.

His left arm was jerking spasmodically and with such power the whole restraint board shuddered. The seizures marched down the left side of his body, and his leg began to thrash as well. Now were lurching, thrusting off the board as the seizures continued inexorable march across his body. The jerking intensified, the restraints scraping his skin bloody. Emma heard a sickening crack the bones of his left forearm snapped. The right wrist restraint apart, and his arm thrashed unchecked, the back of his hand pummeling the edge of the table, smashing bones and flesh.