The 6th Extinction (Sigma Force 10)

“The Volitox are also very intelligent,” Harrington added, looking equally grim. “They hunt in packs, employing a multitude of ambushing techniques. Even our sonic weapons are useless against them.”

Stella scowled. “We lost three men in our early expeditions . . . before we knew better.”

“It’s a harsh, alien world down here,” Harrington conceded. “The survival strategies that have evolved are clever and terrifying.”

Jason stared down at the waters, gone black again, hiding what lurked below.

Sounds like we could use some clever survival strategies of our own.

12:16 P.M.

“They’re gone, sir,” his second-in-command stated.

“I can see that.”

Major Dylan Wright stared at the empty tracks leading out from the observation deck. Fury heated his face, burning as hotly as the bullet graze across his upper thigh. He had lost two men during the raid, all in a rushed attempt to reach Harrington before he could escape.

Bertram and Chessie, he reminded himself, intending to honor the pair when the time was right. But he still had another fifteen men under his command, looking to him for the next move.

“The bombs,” Dylan asked. “What’s the word from Gleeson?”

His second-in-command, a muscular Scotsman named McKinnon, shook his head. “Looks like the base installed a new system after we left. Gleeson might be able to work out a way to defuse them, but not likely in the next half hour.”

It won’t take Harrington that long to reach the Back Door.

Dylan cursed the fact that his team’s activities were exposed sixteen months ago, requiring a fast escape from Hell’s Cape to avoid capture. It had made the rest of his mission troublesome and problematic. Luckily he had the foresight to rig the ice shelf supporting the Halley station with incendiary bunker busters of his own. Hopefully it had taken out the American team. He pictured the man firing at the Twin Otter, smoking out the plane’s starboard engine. His team had barely made it back to their base. Still, they had maintained their schedule.

Until now . . .

“I could send a team overland,” McKinnon offered. “We could ambush them out there.”

“If the base upgraded the security here, they would’ve done the same out there.”

Besides, the Back Door substation was on the far side of the forbidding coastal crags. No team could get there in time to stop Harrington from blowing this place to kingdom come.

And that must not happen.

At least not before I’ve completed my mission.

Failure was not a word in his employer’s vocabulary. Cutter Elwes had paid dearly for his team’s services, including placing hefty bribes and pulling the right strings to get his group assigned to the station as a security detail. Since then they had been feeding Elwes intelligence about this place for years, obeying his every instruction.

And now the endgame was in play.

If successful, the windfall for his team would set them up for life.

McKinnon shifted his feet. “What’s the next step?”

He ran various scenarios through his head, staring out into the dark cavern. Harrington had hightailed it out of here, like a fox before his father’s hounds. But Dylan had never failed in a hunt—not on his family’s country estate, and certainly not now.

His palm came to rest on the holstered nineteenth-century Howdah pistol, one of the rare treasures still in his possession, despite the family falling on hard times these past decades. The gun was a double-barrel weapon, over eighteen inches long, loaded with custom-made .577 cartridges and fired with rebounding twin hammers. The pistol dated back to the time of the British raj, when his family once lived as kings in India. Its name—howdah—came from the saddle worn by elephants, and the large-bore weapon had been used back then to defend against tiger attacks or to hunt large game.

He had even tested the gun here, against the denizens of Hell’s Cape.

His fingers tightened on the grip, preparing for yet another hunt through these dark caverns.

“Gear the men up,” he said. “Load the packages into the CAATs. We’re going after them. Top speed.”

“The professor has a good lead on us,” McKinnon warned.

Dylan sneered, appreciating the challenge.

“Then we’ll have to do something about that.”

12:17 P.M.

A heavy silence had settled across the gondola, each passenger lost in his or her thoughts. All the while, Gray watched the mileage indicator click down. They were only a quarter of the way to this secondary station, the Back Door.

He studied the world beyond their meager refuge. With a long way still to go, he wanted as much information as possible before they reached the end of the line.

“So where did this all come from?” he finally asked, breaking the tense silence. “How could this ecosystem have survived down here for so long without any sunlight?”

“I don’t have an answer to your first question,” Harrington said, “but I have my theories. As to how this ecosystem could have survived, the situation here is not all that different from those oases of life found growing and thriving alongside deep-sea hydrothermal vents. No one expected to find life at those depths, in that eternal darkness, at such extreme temperatures. But nature found a way. The same down here, but on a grander scale.”

Harrington waved a hand to indicate the steaming water. “The ecosystem down here is not driven by the sun, or photosynthesis, but by chemicals—by chemosynthesis. It all starts with chemoautotrophic bacteria that feed on hydrogen sulfide or methane, chemicals continually spewing into this cavern system from all of the local geothermal activity. Those bacteria grow into thick mats—serving a similar role as the grasses of the sunlit world above—fueling the web of life found down here.”

Stella cautioned, “But even chemosynthesis cannot fully explain how all this formed. Like my father mentioned, life down here is xenobiological, foreign to anything seen on the surface.”

“How is it specifically foreign?” Jason asked.

“The life found in this ecosystem is not based on DNA, but on a variant using a different genetic backbone, namely XNA.”

Gray had heard the reports out of California, about how the synthetic organism released by Dr. Hess was an organism engineered with XNA, replacing the normal sugar molecule in DNA with some toxic combination of arsenic and iron phosphate. Here must be the source of that unique genetic element.

“Why does XNA make such a difference?” he asked.