Langdon looked horrified. “Sasha told me she has memory issues. She thinks it’s epilepsy-related.”

  “They may well be,” Katherine replied. “But if Sasha is being given Rohypnol regularly, she would have serious memory impairment…perhaps even no recollection of ever coming here.”

  “Maybe that explains the wheelchair in the transport? They could have been shuttling Sasha back and forth?”

  “It’s quite possible,” Katherine said. “And it makes me think of the other epileptic you mentioned—the man Brigita brought from that same institution? Brigita may have told Sasha that he went home, but these are incredibly dangerous drugs…Anything could have happened. He could have gone insane or died—who knows? One advantage of recruiting a patient who was abandoned in a government institution is that he won’t really be missed if he disappears.”

  Langdon was already heading for the door. “This is starting to make sense,” he said, “and if we’re right…and we can find proof that the CIA is experimenting on innocent test subjects without their knowledge…”

  It would be game over, Katherine realized, imagining the extent of public outrage if this was true.

  Back in the hallway, Langdon was eager to push deeper into Threshold. The main corridor turned sharply right, and he could see two smaller hallways branching off it to the left. The facility was turning into a labyrinth.

  A meandering Cold War bomb shelter…How far does it go?

  He knew they would need to pay close attention if they were going to find their way out of here.

  At the corner, they turned right, keeping with the main corridor. Once again, as they stepped into the darkened space, the floor lights immediately illuminated.

  Not far ahead, a pair of double doors blocked the hall. Langdon felt reassured to note the door’s oval windows were dark, suggesting no lights were on in the area beyond.

  We’re still alone down here…at least in this section.

  They pushed through the double doors into more darkness, and again floor lighting came on to reveal another section of hallway. But something was different here…The air was about ten degrees cooler and carried the faint carbon tang of museum air. Heavily filtered.

  The second thing Langdon noticed was that the hallway was a dead end. The hall offered only a single alcove on the left, about halfway down, which, by all appearances, was the entrance to another suite of some sort.

  Langdon realized that if they didn’t find what they needed in there, they’d have to start venturing off the main hall into other areas. Despite his eidetic memory, he was already getting turned around in this maze.

  As they continued walking, Langdon tried to gauge exactly where beneath Folimanka Park they were now located. He eyed the dead-end wall at the end of the corridor, wondering if perhaps there were tourists milling on the other side of it in the public section of the shelter…unaware of the ominous facility that existed right beside them.

  They turned into the lone alcove and stopped short. In front of them was an oversized glass revolving door with thick rubber gaskets designed to retain air quality. It looked like another lab door, but the space beyond was pitch-black.

  “RTD,” Katherine said, reading three stenciled letters above the revolving door. “Sounds promising.”

  “Does it?” Langdon’s only memory of RTD was from grade school math. Rate x Time = Distance.

  “Research and technical development—it’s the European equivalent of R&D,” she said, peering into the dark glass. “Which means this could be exactly what we’re looking for.”

  CHAPTER 101

  CIA Director Gregory Judd gunned his wife’s Jeep Grand Cherokee down Georgetown Pike toward CIA’s Langley headquarters. His regular driver was not prepared at this early hour, and Judd did not have time to wait. Despite his distaste for Finch’s methods, the director had a duty to country first…and most Americans could not begin to comprehend the threats this country faced.

  America and her allies are under attack…at all times.

  In recent years, their enemies had needed only the most rudimentary social media tools to influence the minds and decisions of millions upon millions of people. His agency had tracked measurable foreign influences over elections, consumer habits, economic decisions, and political trends. But those attacks paled in comparison to the storm that was coming.

  There’s a new battleground emerging, and it requires new kinds of weaponry.

  The Russians, Chinese, and Americans were all racing to dominate this new arena, and winning that race had been Gregory Judd’s primary directive for his entire twenty-year tenure in the upper echelons of the agency. Threshold, and its astonishing technology, was about to give him an edge.

  Now, as he raced toward Langley, he wondered what it was that Ambassador Nagel had sent to his secure server that she believed was explosive enough to hold the CIA hostage.

  A bluff? Doubtful. An overplayed hand? Nagel was too smart for that.

  All he could imagine was she had somehow discovered what they were doing inside Threshold. If that was true, Judd would need to do everything in his power to keep her quiet. If Nagel went public with that kind of sensitive information, the fallout would be explosive—and global.

  Overnight, the psychic arms race would escalate uncontrollably.

  Deep beneath Folimanka Park, The Golěm sat with his back against the heavy metal door, catching his breath.

  I cannot risk another seizure.

  I need to escape alive…I must release Sasha.

  As his pulse slowed, he stood cautiously and gripped the thick wheel mounted to the door. He paused for ten seconds to allow any lightheadedness to clear. Then, with all his strength, he turned the wheel repeatedly until he heard the heavy latch disengage inside. The Golěm pushed the steel portal inward. From out of the blackness beyond, an icy wind whipped past him, lifting his cloak tails as he put his head down and stepped through the airtight opening. The lights inside snapped on, and he heaved the door closed behind him.

  Instantly, the wind subsided.

  The fortified vault in which he was now standing was bitter cold, but he knew this was not air-conditioning. This was Prague winter seeping in. The ceiling had a gaping circular hole in it, more than two meters in diameter. The hole ascended through a vertical steel conduit that climbed several stories through the earth to an ingeniously disguised opening in the middle of Folimanka Park.

  The Golěm had seen the opening many times.

  Everyone had.

  The conduit emerged from the ground, rising about three meters into the air, and was capped with a perforated concrete dome. For decades, to the passersby in the park, it resembled a giant concrete torpedo sticking out of the earth.

  Guidebooks correctly identified it as the original ventilation shaft for the now-defunct Folimanka bomb shelter, and despite many petitions to remove the “torpedo tip” as an unsightly reminder of Cold War times, anonymous street artists had come up with a very different idea. Prague was a city of avant-garde art, and years earlier the concrete vent had been mysteriously transformed. The odd-shaped canvas now paid tribute to one of Hollywood’s most beloved movie stars—a robot who was conveniently shaped exactly like the tip of a torpedo—the droid R2-D2 from Star Wars.

  R2-D2 had become a popular feature in Folimanka Park, towering over all who posed for photos beside its iconic silver, blue, and white body. The city government agreed it was historically appropriate to leave the anonymous art in place, as it actually had been a Czech writer—Karel čapek—who had coined the term “robot” for the very first time in a play he wrote in 1920.

  Of course, from the outside no one would have any idea that this defunct ventilation shaft had been entirely repurposed. It was no longer used to pull air in. Rather, it was now an emergency fail-safe—engineered to let something else out.

  The monotonous patter of rain on Faukman’s windows seemed an apt soundtrack for his latest dead end. Having researched all of In-Q-Tel’s fractal-based investments, he had found nothing that seemed like it could be compromised by Katherine’s writings.

  Fractal telescopes? Fractal cooling components? Fractal stealth geometry?

  Faukman shook his head in frustration as the exhaustion of the night settled deeper into his bones. He couldn’t know for certain, but he suspected that whatever in Katherine’s manuscript had provoked this attack…was far more significant than fractals.

  CHAPTER 102

  As Langdon and Katherine pushed through the revolving door into the RTD facility, they found themselves in a small antechamber—an immaculate glass cubicle with shoe racks, storage cubbies, and a series of hooks holding clean white jumpsuits. In addition, there were two “air showers”—enclosed cubicles with high-velocity jets of filtered air to blow particles and contaminants off clothing and skin.

  Like the narthex of a cathedral, Langdon mused. A room to purify the unclean…before they enter the sanctuary.

  In this case, the sanctuary was apparently whatever lay beyond the glass wall directly in front of them, its entrance delineated by a second airtight revolving door rather than a Gothic arch.

  Katherine was already pushing through the second door, and Langdon followed. The halogen lights that blazed to life overhead were as bright as any Langdon had ever seen. Their brilliance was further amplified by the room’s contents; nearly everything in this huge space was stark white—walls, floor, tables, chairs, work counters, even the plastic coverings on all the equipment.

  “It’s a clean room,” Katherine said.

  Row after row of countertops housed perfectly organized tools, along with electronic devices and machinery beneath plastic protective sheaths. The computer systems looked elaborate, but all the displays were dark.

  Katherine walked into the center of the room while Langdon moved along a side wall, stopping to peer through a window into an adjoining space. On the other side of the glass was some kind of biology lab—microscopes, flasks, petri dishes—much of it unpacked. Against the rear wall—in its own glass isolation booth—stood a piece of equipment that Langdon had never seen.

  The delicate-looking device consisted of hundreds of long glass vials that hung down vertically through a perforated platform. Each appeared to be fed by its own ultrathin tube that descended from the upper body of the machine. It reminded Langdon vaguely of a precision hydroponic drip system he had once seen at an indigo exhibition. Are they growing something in there?

  “Over here,” Katherine said, standing beside a large contraption that was about three feet tall and looked like some kind of futuristic Rube Goldberg invention. Langdon headed over to her and examined the device.

  “It’s a photolithograph,” she said.

  Langdon sensed his knowledge of Greek was about to fail him. “So, it writes…on rocks…with light?”

  “Exactly,” she said. “Provided the light is deep ultraviolet…and the rock is a silicon wafer.” She motioned to a stack of glossy metallic disks sitting beside the machine. “This lab has everything required to design and build custom computer chips.”

  Computer chips? The notion seemed totally unrelated to human consciousness or to whatever Katherine might have written about in her manuscript. “Why would they be designing computer chips down here?”

  “My best guess,” Katherine said, “is brain implants.”

  The idea startled him, but he quickly made the connection. “The robotic brain surgeon…”

  “Exactly. I think I was wrong when I guessed it was extracting brain samples. It seems pretty clear the robot is used for implanting brain chips.”

  An uneasy silence settled in the bright room.

  “Didn’t you say brain implants were basic surgery?” Langdon asked.

  “Epilepsy chips, yes. They’re tiny electric shock machines embedded in the skull. But an advanced implant would be more deeply placed and would definitely benefit from robotic surgery for implementation.”

  Langdon thought about Sasha and felt a trace of dread. He wondered if she could have been implanted with a prototype chip—probably under the guise of an epilepsy procedure. She would have no idea what was really inside her head…or that Threshold even existed, for that matter.

  “If Gessner lied,” Langdon said, “and the implant she put into Sasha was actually a more advanced, subcranial chip…”

  “Then that implant could easily function as the RLS stim device to control Sasha’s epileptic seizures, and yet, at the same time…it could have countless other functions.”

  “I hesitate to ask…like what?”

  Katherine tapped her index finger on the top of the photolithograph machine, thinking. “There’s no way to know without examining the chip,” she said. “But it looks like they’re starting to build them here. I’m guessing Sasha and that other male subject were probably their first patients…an initial validation study and proof of concept before shifting this facility into high gear.”

  Langdon felt intensely disturbed by what he was hearing.

  “Whatever they did,” Katherine said, “it must have gone well, because Threshold is clearly gearing up for a larger-scale operation.” She glanced around the room and frowned. “Unfortunately, there’s nothing specifically incriminating here. All it proves is the CIA appears to be developing some kind of brain implant—a project that would surprise absolutely nobody.”

  True, Langdon realized. Brain implants are the future.

  Langdon had read enough science columns to know that implanted brain chips, despite conjuring images of cyborgs and science fiction, were already functional and startlingly advanced.

  Companies like Elon Musk’s Neuralink had been working since 2016 to develop what was known as an H2M interface—human to machine—a device that could convert data obtained from the brain into understandable binary code. One of Musk’s first milestones had been to implant a monkey with a Neuralink chip and teach it to play the computer game Pong using only its brain impulses to move the paddle.

  When Neuralink had finally received FDA clearance to test on humans, they had implanted Noland Arbaugh, a thirty-year-old quadriplegic, with a device called PRIME and miraculously returned a fair number of the patient’s motor skills. Unfortunately, after only a hundred days, the chip’s electronic threads—the metallic sensors by which the chip communicated with the brain’s neurons—retracted from the brain, apparently rejected by the biological neurons they were supposed to monitor. Nonetheless, it was a substantial leap forward.

  Other industry leaders like Bill Gates and Jeff Bezos’s Synchron, along with BlackRock’s Neurotech, were designing less invasive, more specialized chips that they claimed would accomplish stunning results such as overcoming blindness, curing paralysis, overcoming neurological disorders like Parkinson’s, and even providing “type with your mind” capability.

  Although Langdon was still unclear on this technology’s link to human consciousness and Katherine’s work, he had no doubt that brain chips would have critical implications for military intelligence—drones piloted by the mind, telepathic battlefield communication, endless applications for data analysis—so it made perfect sense that the CIA would be investing heavily.

  Human-to-machine interface is the future.

  Langdon recalled what he had witnessed at the Barcelona Supercomputing Center, where modeling software was predicting the future evolution of the human race: HUMANS WILL MERGE WITH ANOTHER QUICKLY EVOLVING SPECIES…TECHNOLOGY.

  “Okay, so the key question is, where does this intersect with your manuscript?” Langdon pressed, eager to find the connection. “Did you write about computer chips?”

  “A little bit,” she said, visibly frustrated, “but it’s nothing that could be of any interest or threat to this program.”

  “Are you sure?”

  “Yes. My only mention of brain implants was in the final chapter, and it was more of a theoretical narrative musing about the future of noetic science.”

  Noetics Tomorrow, Langdon thought, having glimpsed her chapter index before adding it to the fire in the library. “And brain implants played a role in that chapter?” he urged, sensing they might be close.

  “Hypothetical implants, yes,” she said. “Implants we won’t have for decades…if ever.”

  Langdon had once heard that the technology available to the intelligence community was years beyond what was known publicly. “Katherine, is it possible that the CIA is further along than you imagine?”

  “It’s possible, but not that much further,” she said. “What I wrote about is more of a thought experiment, rather than a plausible technology. Think of Maxwell’s demon or the twin paradox—obviously you can’t invent a molecule-sorting demon or propel twins to the speed of light, but imagining it is helpful in understanding the bigger picture.”

  I’ll take your word for it, he thought. “Tell me what you wrote.”

  Katherine sighed. “It was a fantasy relating to my discoveries about GABA. Remember we talked about the brain being a receiver…a kind of radio that receives signals from all around us—from the universe?”

  Langdon nodded. “And the brain chemical GABA functions like the radio dial…filtering out unwanted frequencies and limiting the amount of information and consciousness that flows in.”

  “Precisely,” she said. “So I hypothesized that one day, in the distant future, we would figure out how to build an implant that could regulate GABA levels in the brain—essentially lowering our filters on demand…so we could experience more of reality.”

  “Incredible,” Langdon said. The mere thought of it was thrilling. “And that’s not possible?”

  “God, no!” she said, shaking her head. “The most advanced noetic science is not even in that ballpark yet. In the first place, we would have to be correct about the noetic theory of a Universal Consciousness or the Akashic Field or Anima Mundi—or whatever you want to call the field of consciousness that is theorized to surround all things.”