point-six kilometers. She’s moving, about three meters per second. It’s a good bet she’s still in the river.”

“It’s been two hours,” Niwara said. “I hope for her sake she’s a strong swimmer.”

Returning the tricorder to his hip, he replied, “Only one way to find out, Lieutenant. Take us downriver.”

Niwara continued forward along the cliff trail, and Terrell followed a few meters behind her. He hoped that Theriault was still alive and conscious, and that she could halt her journey on the river soon. Moving on foot, he and Niwara would only fall farther behind Theriault the longer she remained in the river.

As for whether the young science officer would be able to survive for two hours or more trapped in a raging current, he could only pray for the best and keep walking in slow pursuit.

Dr. Lisa Babitz hated germs. Most people she had ever known weren’t fond of infectious bacteria, but the blond surgeon reviled them with a passion that bordered on the pathological.

Keeping every surface of the interior of the Sagittarius clean and disinfected had been a challenge since her first day aboard, due in no small part to the habits of her crewmates. In the few short years that they had served together, she had learned to tolerate Ilucci’s penchant for eating with hands unwashed after working in engineering, Threx’s knack for leaving thick wads of shed body hair in the single shower that the entire crew shared, and even Lieutenant Niwara’s disturbing method of cleaning herself. In return, they had come to ignore her practice of conspicuously sanitizing every crew compartment on the ship at least once every other day.

Now there was mud in her sickbay.

There was mud, and trampled vegetation, and puddles of dirty water, tracked in long paths throughout the ship.

Worst of all, Lieutenant Commander McLellan, who was lying anesthetized on the biobed in front of her, and medical technician Tan Bao, who was standing on the other side of the bed, both were mummified in brown sludge. Just looking at them plagued Babitz with sensations of phantom insects creeping across her skin. She took a deep breath and searched in vain for calm.

Struggling to keep her tone professional, she instructed Tan Bao, “Cut away the fabric above the wound.” Tan Bao carefully sliced away several centimeters of the soiled green fabric. Babitz squinted at the unusual substance that had aggregated over McLellan’s wound. “Can you wash that?” she asked Tan Bao. “I want to get a clear look at it.”

“Yes, Doctor,” Tan Bao said, and he set to work rinsing the dirt and debris from McLellan’s leg. While he worked, Babitz reviewed the data from Tan Bao’s tricorder. The molecular structure of the crystalline substance on McLellan’s leg was very similar to one that Babitz had noted in an autopsy file Xiong had provided as part of her preparation for the mission.

Tan Bao interrupted her ruminations. “Doctor? The wound’s clean and ready for examination.” He stepped back to give Babitz more light.

She leaned down and eyed the dark, glasslike substance. “Hand me a two-millimeter biopsy punch,” she said. Tan Bao passed her the instrument, and she positioned it with care and precision above the thickest portion of the crystalline scab. With a quick jab, the punch penetrated its surface and came away with a tiny chunk of the substance lodged inside its circular cavity. She handed it back to Tan Bao. “Run a full-spectrum scan on this.” The technician nodded and carried the sample away to a compact analyzer on the other side of sickbay.

Babitz turned her attention to McLellan’s severed limb. The lower half of the woman’s right leg was cocooned in the peculiar crystal. She set it on the sickbay’s second biobed, from which she had only minutes earlier ejected engineer Torvin. A pallet of scanners mounted above the bed hummed as she powered them up. The indicators shifted on the bed’s display board. Babitz lifted her own tricorder and downloaded more complete results from the sickbay computer.

The severed leg showed no evidence of putrefaction. It had been all but completely mineralized by contact with the alien crystalline substance. Like petrified wood, Babitz thought. Except almost instantaneous. Impatient to verify her findings, she called up the autopsy report she had remembered from her pre-mission briefing. It took only seconds to find it.

Drs. Fisher and M’Benga had conducted an autopsy on the body of a Denobulan named Bohanon. According to the file, the man had been killed on Erilon during an encounter with a Shedai entity, slain instantly. His body had been returned in stasis to Vanguard, but as soon as it had been taken out of stasis for analysis something remarkable had occurred. Anabolic activity had been detected on all the exposed internal tissues contacted by the Shedai combatant. Some kind of alien bio-residue had started to transform the Denobulan’s organic tissues into a substance resembling a crystalline lattice. Fisher had noted that the process was short-lived, penetrating only a few millimeters into the surrounding tissue—but he also had speculated that the process might not be so abbreviated in a living subject.

Working quickly, Babitz placed McLellan’s crystallized leg into a stasis module, then returned to the woman’s side and initiated a new scan on the stump of her right leg.

She was still comparing her results to Tan Bao’s original scan of McLellan’s injury when the technician looked up from the analyzer and swiveled his chair to face her. “It’s a living crystal matrix,” he said with amazement. “A mineral composite with anabolic properties.” He added more ominously, “Just like what the Vanguard team found in that thing they brought back from Erilon, except…alive.”

“That’s not all, Tan,” Babitz said. “It’s spreading. Two hours ago, this substance penetrated two millimeters up her thigh. Now it’s twenty-two millimeters along. If it continues at this rate, it’ll start hitting vital organs in less than thirty-six hours. And in forty-eight…she’ll be dead.”

Theriault had lost any sense of how long she had been in the water. It had carried her through multiple sets of rapids, across clusters of half-submerged boulders, over sudden plunges into rock-bottomed shallows. Her entire body was covered with scrapes and bruises.

Her fall from the cliff had seemed to happen in slow motion. Succumbing to gravity’s pull, her senses had sharpened, and she had seen all the vines between her and the river. Her hands had grasped in vain at every one within reach, and they all had snapped under the force of her plummeting body.

Striking the water had been a stunning blow. Disoriented from the impact and the irresistible pull of the current, Theriault had spent several seconds fighting her way to the surface. Her first instinct had been to swim for one bank or the other, but the rocky walls of the winding ravine had offered her no handholds, no means of pulling herself from the water.

Little by little, the clifftops had drawn closer, the ravine had narrowed, and the water had gained speed. Now it emerged from the rocky gorge into a lush rain forest of azure. The river was wider here, and though Theriault now could see flat riverbanks on either side of her, she was too weak to fight across the current to reach them. It took all her flagging strength to keep her head above the surface, to gasp for breath without swallowing the silt-rich water.

The jungle was eerily quiet. There was no sound except her own labored breath and the splashing of her exhausted limbs. Have to conserve my energy, she reminded herself. Rest before I hit more rapids. She took a deep breath, then closed her eyes and rolled facedown into the river. Relaxing her arms first and then her legs, she let her limbs dangle beneath her as she floated limp in the current, letting it take her without a fight. After struggling for so long, she relished being able to rest her weary body, even if just for a minute.