Rafaele Buonarroti crawled along the Jefferies tube, the metal grating hard against his knees even through the material of the environmental suit he wore. A loud, deep drone filled the area, joined by a higher-pitched, tremulous whine. The sounds conducted through the air, through the decking, through the environmental suit, causing a sensation like insects crawling all over his body. Normal engineering procedures restricted access to this section of the ship when the impulse engines were engaged, but the situation right now had deviated far from normal.

Buonarroti tilted his head—an awkward movement with his helmet on—and peered past his feet to where Lieutenant Trent clambered along after him. They’d left their comm channels open, and Buonarroti heard Trent’s breathing beginning to become a bit labored. “Are you all right, Gray?” he asked, having to raise his voice to be heard above the ambient sounds of the drive.

“Yeah,”Trent said around mouthfuls of air. “I’m okay. It’s just a little hot in here.”

“Don’t worry about the heat,” Buonarroti quipped. “Long before we burn up, the radiation will kill us.” Trent actually laughed at that, despite the truth contained in the joke. While the environmental suits would have safeguarded them from the standard temperature and radiation levels of the impulse engines for a matter of hours, now they would provide only minutes of protection. Lieutenant Commander Linojj had been able to shut down the starboard engine, but the port reactor remained online, deuterium fuel apparently flowing uncontrolled into its core. And that meant that somebody had to come here to attempt a repair of the problem.

Buonarroti looked ahead again, pulling himself along in the enclosed space. He glanced at the data on the readout strip sliding down the left side of his faceplate, and saw that he and Trent had only thirteen minutes left before the radiation levels here would begin affecting their bodies. The sections surrounding the port impulse engine, he knew, were already being evacuated.

A minute later, Buonarroti arrived at the engineering panel that allowed access to the deuterium-flow regulator for the port reactor. He stopped and climbed onto his knees, then reached forward to remove the panel, his movements slowed by the environmental suit. The panel came away from the bulkhead easily, the magnetic locks giving way under the force of his pull. He set it to one side and peered in at the regulator. A readout on it indicated the runaway nature of the hydrogen-isotope stream pouring through its electromagnetic control field.

Buonarroti believed that the symptoms of the problem pointed to a disruption of that control field. That likely meant either a physical defect or a programmatic problem in the regulator; because the diagnostic code in the firmware had failed to identify any physical defects, he therefore suspected the latter, which was why he had brought Trent down here with him. It had also occurred to Buonarroti that Enterprise,sitting docked at a Romulan space station, might have been sabotaged, but at the moment that possibility mattered little to him; he only cared about diagnosing and then repairing the problem.

He pulled a tricorder from where it hung on his environmental suit, along with two fiber-optic leads. He quickly attached the thin glass wires to the tricorder, then reached in and connected the other ends to the regulator. He worked the controls on both devices, scrutinizing their displays. He had expected the root cause of the problem to reveal itself immediately, but instead, he detected nothing wrong.

On his faceplate, he saw that he and Trent had only ten minutes of safety left. If they had not fixed the problem in that time, he knew that they would continue to search for a solution, but their probability of surviving the situation unharmed, if at all, would rapidly decrease to zero.

“Gray,” Buonarroti said, and he handed the tricorder to Trent. The computer scientist took it, holding it in both of his gloved hands, his strained breathing loud over the comm system. He studied the readout for just a few seconds.

“There’s nothing wrong here,”he said. “The operating system is functioning perfectly.”

“But how can there be no problem to report,” Buonarroti asked, “when there clearly isa problem?”

Trent nodded. “Let me check the verification routines.”He operated the controls of the tricorder, then looked up and pointed into the bulkhead at the regulator. “I need to get in there,”he said.

Buonarroti quickly scrambled farther down the Jefferies tube, clearing the way for Trent in front of the engineering panel. Trent moved forward as well, then reached inside. Buonarroti watched as the lieutenant pressed the control pad on the regulator, causing text—lines of code, Buonarroti assumed—to march across its display.

A minute passed. Then another. Buonarroti felt perspiration rolling down his body inside the environmental suit, a result not of the heat, he thought, so much as of the time growing short. He imagined the heavy atoms of hydrogen screaming past the regulator, unconstrained as they fed the fusion reactions in the impulse engine. Like having too many logs on a fire, the increase in the number of atomic reactions in the core would eventually generate more energy than could be contained in the reactor.

Seven minutes left.

“I’ve got it,”Trent said at last. “The diagnostics aren’t checking out. The checksum routines seem to be off.”He worked the controls on the regulator’s panel for a moment more, then began operating the tricorder

“Can you fix it?” Buonarroti asked.

“I’m trying,”Trent said. “I’m recoding the safety routines, reestablishing the parity bits.”

Six minutes left. Then five.

“Uploading,”Trent said, peering into the bulkhead. Buonarroti followed his gaze, and saw a warning message scroll across the regulator display. Around them, the resonant hum of the port impulse engine, along with the sickly whine permeating it, began to fade. He looked up at Trent. “Error detection is now functioning,”the computer scientist said. “There’s a flaw in the regulator surface. Automatic shutdown is in progress.”

Buonarroti leaned in beside Trent and touched a control on the tricorder. Sensor readings of the reactor core appeared on the display. The radiation and temperature levels had stopped their precipitous climbs, and as he watched, they even began to recede.

“Let’s get out of here,” Buonarroti said, pointing past Trent back down the Jefferies tube.

“Bridge to Buonarroti.”Sulu’s voice came over the comm system as the two men began to crawl back the way they had come. “You’ve done it.”

“Yes, Captain,” Buonarroti confirmed. “Trent did.”

“Good work,”Sulu said.

“We’re on our way back to the bridge,” Buonarroti said.

“I look forward to your report,”Sulu said. “Out.”As the two made their way through the Jefferies tube toward the corridor, Buonarroti checked the readout on his faceplate. Seconds continued to tick off from their margin of safety. 3:57. 3:56. 3:55.

“We had more than four minutes left,” Buonarroti told Trent. “That wasn’t even dramatic.”

“Sorry,” Trent said. “Next time.”

“Yeah, next time,” Buonarroti agreed. “I can hardly wait.”

Sulu noticed the eyes first. The gray irises mimicked the color of ash, and appeared as cold as the remnants of a fire long extinguished. The glare of the Romulan admiral felt penetrating, even on the viewscreen.

“We have replaced the defective part,” Sulu said, standing at the center of the bridge, directly behind Linojj and Tolek at the helm and navigation stations. The admiral regarded her impassively. So thin that he could almost be called gaunt, he had straight, silvering hair and deep lines drawn around his mouth.