The Kill Switch

He shifted the sample of LUCA. “And here we have the earlier common ancestor, the stem cells of the flora world, if you will.”

Tucker pictured the microcosm of that ancient world found in the cave. “And the two were in competition?”

“Most definitely. In that harsh primordial time, it was a wi

“And what we saw in the cave?”

“A snapshot of that ancient battle. But as in all wars, often common ground is found, cooperation necessary for short periods of time. What we witnessed below was an uneasy détente, two enemies helping each other survive in such strict isolation. Both needed the other to live.”

“Why do you think that?”

“During my studies here, I found healthy LUCA bulbs with dead lichen melting deep inside, being consumed. I believe living lichen can kill LUCA and use it as some fertilizer source. While at the same time, as the lichen die and flake from the roof and walls, it feeds the LUCA below, raining down, landing on those broad mushroomlike growths.”

“You’re saying they were feeding off each other.”

“That. And I’m sure the constant flow of water through the chamber brought a thin and steady flow of nutrients and biomatter to them as well. I also think their relationship was more nuanced, that they helped each other out in other ways. Perhaps the lichen’s bioluminescence served some beneficial advantage to the LUCA, while the sulfur-rich gas—that stink we smelled down there—given off by the germinating bulbs helped the lichen in some ma

“And how does that help us find the kill switch?”

Bukolov held up a finger. “First, we know that the living lichen can kill LUCA, but not dead lichen. So that knowledge alone will help me narrow my search for the chemical kill switch.”

He raised a second finger. “Two, we know who won that ancient battle. LUCA was vanquished, all but this small isolated garden, leaving behind only its genetic legacy in the form of modern plants. But cyanobacteria survive today, going by their more common name: blue-green algae. Because of their versatility, you can find cyanobacteria in every aquatic and terrestrial location on the planet, from the coldest tundra to the hottest volcanic vent, from freshwater ponds to sun-blasted desert rock. They are masters of disguise, merging with other organisms, like with the lichen here, but also with other plants, sponges, and bacteria. They can even be found growing in the fur of sloths.”

“It almost sounds like your description of LUCA from before. An organism with limitless potential.”

“Exactly!” Bukolov stared over at Tucker. “That’s because cyanobacteria are the closest living organisms to LUCA today. But from my studies—on a purely genetic scale—LUCA is a thousandfold more efficient, aggressive, and tough. Released today, unchecked and untamed, LUCA would wreak untold ecological havoc across every terrain on Earth, both land and sea.”

“But, Doc, it was defeated in the past. Like you said, it didn’t survive.”

“And that’s the second clue to discovering the kill switch: Why didn’t LUCA survive, while cyanobacteria did?”

Tucker had to say he was impressed with how much Doctor Bukolov had learned in such a short time. He could only imagine what he could accomplish with Sigma’s laboratory resources in the States.

“I have much to ponder,” Bukolov said.

Tucker’s satellite phone buzzed in his pocket. “Then I’ll leave you to it.”

He headed out of the room and answered the call.

“How are you all doing out there?” Harper asked as the line co

“More than ready.”

“I talked to the military biologists over at Fort Detrick, and they wanted to know if Doctor Bukolov had any estimate on how long it would take Kharzin to weaponize his sample of LUCA.”

“That’s just it. According to Bukolov, it would take very little engineering. It’s a ready-made weapon. All that he really needs to figure out is the method of delivery and dispersal.”

“And how long would it take General Kharzin to do that? It seems Bukolov knows this man and his resources fairly well.”

“No more than a week.”

“Not much time,” she said dourly. “And is Bukolov any further along with the kill switch?”

“Some progress, but any real answers will have to be worked out back in the States.”

“Then I have one last question. From Bukolov’s assessment of the general’s personality, would Kharzin unleash this bioweapon without that kill switch.”

“In other words, how much of a madman is he?”

“That’s about it.”

“I don’t have to ask Bukolov.” Tucker reviewed his dealings with Kharzin from Vladivostok to now. “He’ll test it. And he’ll do it soon.”

42

March 26, 7:57 A.M.

Frederick, Maryland

With a puff of pressurized air, Tucker crossed out of an airlock into the BSL-3 laboratory. He wore a containment suit and mask, much like the men and women bustling within the long, narrow space. He imagined there were more Ph.D.s in this lab than there were test tubes—of which there were a lot. Across the vaulted space, tables were crowded with bubbling vessels, spiral tubing, glowing Bunsen burners, and slowly filling beakers. Elsewhere, stacks of equipment monitored and churned out data, scrolling across computer screens.

Orchestrating this chaos like a mad conductor was Abram Bukolov. The Russian doctor moved from workstation to workstation like a nervous bird, gesticulating here, touching a shoulder there, whispering in an ear, or loudly berating.

These poor souls are going to need a vacation after this.

The biolab lay in the basement of a research building on the grounds of Fort Detrick, a twelve-hundred-acre campus that once was home to the U.S. biological weapons program before it was halted in 1969. But that legacy lived on, as Fort Detrick continued to be the military’s biodefense headquarters, home to multiple interdisciplinary agencies, including USAMRIID, the U.S. Army Medical Research Institute of Infectious Diseases. They were currently in the building that housed the Foreign Disease Weed Science Unit, part of the Department of Agriculture.

It seemed the U.S. military was already well aware of the national security threat posed by invasive species. Today that caution paid off, as they mobilized scientists from across the entire campus of Fort Detrick to tackle the threat posed by a weaponized form of LUCA.

Bukolov finally noted Tucker’s arrival and lifted an arm, waving him to his side, which proved a difficult task as the doctor headed away from him, deeper into the lab. Tucker excused his way through the chaotic landscape, finally reaching Bukolov beside a table holding a five-liter glass beaker with a distillate slowly dripping into it from some condensation array. The liquid looked like burned coffee.

“This is it!” Bukolov expounded, his voice slightly muffled by his mask.

“Which is what?”

Tucker had been summoned here this morning by an urgent call from the good doctor, pulled from his temporary accommodations on base. He had been kept in the dark about what was going on at the labs here since they landed three days go in D.C. He and Bukolov had been whisked straight here under military escort.

“I was able to crack the lichen’s code.” He waved a half-dismissive hand toward the team around him, giving them minimal credit. “It was just a matter of determining what it was in living lichen that became inert or dissipated after it died. I won’t bore you with the technical details, but we were able to finally distill the chemicals that created that burn, that killed LUCA cells on contact. In the end, it wasn’t just one chemical but a mix. A precise solution of sulfuric, perchloric, and nitric—all acids.”