“Well, we can publish it now,” Katherine said, motioning to the classified binder in his hand. “Complete with PALM of an implanted brain. Pretty conclusive proof.”

  “What is PALM?”

  “Photoactivated localization microscopy—a brain imaging technique. Threshold genetically encoded their artificial neurons with fluorescent proteins so they could, in effect, see them…and track their growth. Clever idea—theirs, not mine.”

  “Wait, are there images in this binder?! You didn’t—”

  “You took it away too fast,” she said, holding her hands out for the binder. “I’ll show you.”

  Langdon thrust the binder eagerly back into her hands. Despite their evidence that the CIA had stolen Katherine’s idea and was building artificial neurons, Langdon had seen no actual proof that Threshold was doing human trials. This could be it…

  “Here’s a good one,” Katherine said, laying the open binder on the counter before them.

  When Langdon saw the image, he felt both repulsed…and vindicated. The colorful photo resembled a computer-enhanced X-ray of a human brain inside a skull. What was horrifying, however, was what else was inside the skull with the brain.

  Beneath the bone of the skull, a surprisingly large computer chip was nestled into the brain tissue. Attached to the chip a cord snaked to an illuminated mesh of fluorescent threads that seemed to be woven into a lacy, weblike cap, similar to a hairnet, and pulled down over the top of the brain.

  “That neural mesh,” Katherine said. “My idea.”

  Langdon looked on in amazement as she flipped through various images, graphs, and notes monitoring the implant’s progress over time. The records were startling, but the bigger shock came when Langdon noticed the tiny footer at the bottom of every page.

  PATIENT #002 / VESNA

  “Sasha…” Langdon whispered, his worst fears now confirmed. What have they done to you?

  Langdon felt sickened to see the thick mesh of tentacles spread out over Sasha’s brain like some kind of parasite. Ironically, he and Katherine had broken into Threshold to find incriminating evidence…only to learn that the single most incriminating piece of evidence was on the outside, inside Sasha Vesna’s head.

  I hope the ambassador has located Sasha, he thought, again sensing it was time to go.

  “Whatever Ms. Vesna has in her head,” Katherine said, “it does a lot more than cure epilepsy.”

  “Is there anything here that describes what the chip does?”

  “Nothing specific,” Katherine said, flipping pages. “This binder is all about neural integration, and I have to admit, I am amazed they’re achieving integration so quickly.”

  “What do you mean?”

  “Integration between chip and brain,” she said. “Once you lay an artificial neural mesh on a living brain, the two elements need time to fuse into one system. Neural plasticity is a miracle, but it doesn’t happen overnight. For a brain to synapse fully with a neural implant would take at least a decade—maybe two. It’s one of the big obstacles I mentioned in my grad thesis.”

  “What did you propose as a solution?”

  “I didn’t,” Katherine replied. “There is no solution but to wait. Biological growth takes time. Evolution takes time. And yet somehow…” She studied a series of graphs, shaking her head. “They’ve accelerated the process with remarkable speed. In a year, they’ve done what should have taken at least a decade. The question…is how?” She kept flipping pages, passing one on which appeared a tiny headshot of a younger Sasha Vesna with long blond hair.

  “I have a different question,” Langdon said. “If Sasha is patient number two…”

  Katherine glanced up. “Right, then who is patient number one?”

  She immediately began flipping backward through the binder, looking for information on patient number one, who Langdon assumed was most likely the Russian epilepsy patient, Dmitri, from the same institution as Sasha.

  “This is strange,” Katherine said. “I don’t see any section with data on any other—oh, wait—here it is. It’s much shorter. I missed it.”

  The section included assorted data, graphs, and a similarly eerie X-ray of the subject’s brain showing an implanted chip and neural mesh.

  The footer read:

  PATIENT #001 / SYSEVICH

  Sysevich certainly sounds Russian, Langdon thought.

  “Handsome man,” Katherine said, having turned to a page bearing a small headshot of a striking, square-jawed man with curly black hair. His features were clearly Slavic, sturdy and commanding, and yet his eyes had an unsettlingly lifeless gaze. “This guy was clearly implanted with the same chip as Sasha,” Katherine said, still reading. “But it’s weird—there’s absolutely no data post-op. Nothing.”

  “We can talk on the way out,” Langdon said, heading for the revolving door. “We’ve got to get out of here.”

  Katherine closed the binder and slipped it into her shoulder bag. “I hate to say it, but his records end too abruptly. Zero follow-up. It’s like they put the chip in, and…something went wrong. Maybe he died.”

  The thought was disturbing, and yet it added additional ammunition to the leverage they would have; if the CIA experimented on and killed an unsuspecting Russian epilepsy patient, the diplomatic fallout could have dire repercussions in a world already on edge.

  As they pushed through the revolving door back into the hallway, Langdon was reassured to find the corridor pitch-black, its lights having timed out while they were in the lab.

  We’re still alone down here.

  The floor lighting immediately came on, and Langdon and Katherine turned back toward the double doors through which they had come.

  They had taken only a few steps when Katherine grabbed Langdon’s arm. “Look!” she whispered, pointing dead ahead to the doors with the oval windows.

  Langdon had seen it too.

  The lights on the other side of that door had just blazed to life.

  Having completed his thorough search of the medical area, Finch had continued around the corner, where the floor lighting came on to illuminate his path to the double doors at the end of the hall. Taking no chances, he took a moment to stick his head into Immersive Computing, where he was relieved to find all the VR chairs empty and helmets in order.

  Then he saw the desk chair on its side.

  And the cracked glass in the computer room window.

  Normally Finch would have dashed over to check the computer, but he had just had a far more alarming realization—a delayed reaction to something he had glimpsed only moments earlier in the hallway…a soft glow coming through the oval windows of the double doors.

  The lights in the RTD hallway were on.

  Someone is coming!

  Whether a cleaning crew, a security guard, or worse, Langdon knew he and Katherine could not afford to be seen. Unfortunately, they were trapped in a dead-end corridor with no way out except the way they had come.

  Langdon rushed back toward the RTD lab, hoping to find somewhere to hide, but as he neared the clean room door, he realized Katherine had stopped in the middle of the hallway and was pointing at the floor. “Robert,” she whispered. “These are tire marks!”

  Langdon had seen the marks earlier—a trail of scuff marks worn into the polished floor by the treads of the forklift.

  To his confusion, Katherine immediately sprinted past him, waving for him to follow her toward the dead end. What is she doing?! There’s no exit! A moment later, Langdon spotted what Katherine had seen: the wear of tire tracks continued down the hallway and disappeared…beneath the far wall.

  Impossible…unless…

  Langdon broke into a full sprint, pulling even with Katherine fifteen yards from the end of the hall. He spotted the electric eye and ran toward it, waving to activate the sensor. The entire wall began to slide, retracting smoothly to the left, revealing another section of darkened corridor beyond.

  The air emerging from the opening was noticeably colder.

  Without breaking stride, he and Katherine ran through the opening and within a few yards plunged into sudden darkness. They came to a stop at a metal railing just as the retracting wall closed behind them.

  Soft lighting swelled to reveal their surroundings. Langdon was startled to see they were standing atop a concrete ramp that wound downward around the perimeter of a narrow shaft. As he peered over the railing into the darkness below, he realized that Threshold was indeed considerably larger than what they had seen…and it continued in an unnerving direction.

  Down.

  CHAPTER 107

  Ambassador Nagel hurried down the embassy’s marble staircase, feeling somewhat unsteady, which wasn’t all that surprising considering she had just strong-armed the CIA director and drained an afternoon cocktail.

  Where the hell is Dana?

  Sergeant Scott Kerble had promised to escort the publicity liaison upstairs to speak to the ambassador, but Dana had never shown up. Oddly, Kerble was nowhere to be seen either.

  When Nagel arrived at Dana’s office, the willowy publicity liaison was on her hands and knees, tearfully packing up personal belongings and piling them into a cardboard box. Dana glanced up, bloodshot eyes flashing disdain, then went back to packing.

  Not good.

  The ambassador took a moment and centered herself before speaking. “Ms. Daněk, did Scott Kerble ask you to come to my office?”

  “He did.”

  “And you ignored him?”

  “I don’t work for you anymore,” she said bitterly.

  Nagel took a deep breath, entering and closing the door behind her. “Dana, I can see you’re upset. I too cared deeply for Michael Harris, but—”

  “To je lež,” she muttered without looking up.

  “I did care about Michael,” she insisted, “and I will never forgive myself for putting him in harm’s way. I was pressured by my superiors. It was wrong, and I’m ashamed. I will explain it all to you at some point, but right now it’s critical we locate Sasha Vesna, and I desperately need your help.”

  “Why would I ever help you?!” Dana fired back. “You should have known better than to force Michael into a romance with a stranger—a stranger who ended up killing him!”

  “Sasha did not kill Michael,” Nagel assured her. “The truth is that Sasha is in substantial danger herself—probably from the same person who killed Michael—and I need you to help me find her as soon as possible.”

  “Why do you care so much about her?”

  Nagel moved closer and lowered her voice to a whisper. “Dana, I’m ashamed to say this, but like Michael…Sasha is a victim of my government.” She’s a CIA asset…and doesn’t even know it. “I feel a duty to help her.” She paused, holding Dana’s gaze. “And I believe Michael would have wanted you to help Sasha too.”

  The statuesque young woman shivered suddenly, wrapping her arms around herself and setting her jaw tightly as if trying to fend off tears. Nagel was reminded that when someone was as strikingly beautiful as Dana Daněk, it was easy to forget their human frailties.

  “I could never trust you again,” Dana said, her voice cracking.

  “I’ve got absolutely nothing left to lose,” Nagel replied. “Dana, I’m trying to buy my soul back at any cost. And for whatever it’s worth, I just burned my last bridge. I called my old boss and threatened the U.S. government.”

  Dana looked skeptical. “Your old boss? You threatened the director of the CIA?”

  “I did.” Nagel gave her a tight smile. “As I said, nothing left to lose. I’ve just learned some extremely disturbing news about a program I helped facilitate, and my only hope of stopping it and proving my own innocence is a video I just received—a deathbed confession by the program’s principl—”

  “Ambassador?” a man said behind her.

  Nagel spun to see the face of Sergeant Scott Kerble, peering through the narrow opening of the door he had just quietly opened.

  “Most people knock,” Dana snapped.

  “Scott?” Nagel said. “Where were you? You were supposed—”

  “I’m sorry, ma’am.” His voice sounded uncharacteristically stern. “I’m afraid I’ve been ordered to detain you.”

  Nagel eyed her trusted security guard, having little doubt what had just transpired. “Ordered by the director of the CIA?”

  “Please come with me.”

  “You can’t arrest the ambassador!” Dana said. “She’s your boss!”

  Kerble shook his head. “We’re U.S. military.”

  Dana looked at Nagel, who confirmed it with a nod. Unfortunately, Marine security guards took their orders from much higher up the food chain. The ambassador now deeply regretted her decision to entrust Kerble with the diplomatic pouch. My only copy of the video…

  “Madam Ambassador?” Kerble looked genuinely uncomfortable. “Please come with me.”

  “Of course, Scott. I just need a moment. Ms. Daněk has tendered her resignation, and I’d like a private moment to say goodb—”

  “Hands in front of you!” a deep voice commanded as the door swung open to reveal two other Marines waiting behind Kerble. They apparently felt duty bound to support their lead agent whose courtesy was getting him nowhere.

  “Handcuffs won’t be necessary,” Nagel said. “I’ll come quietly, but I’d like a quick word with Ms.—”

  “That’s not possible,” the first Marine barked, moving through the door. “Show me your wrists, ma’am.”

  Incredulous, Nagel looked to Kerble, whose expression had turned decidedly colder in the presence of his fellow agents.

  “Give him your wrists,” Kerble commanded. “And not another word with Ms. Daněk. We have orders. No further contact with anyone. We’ve sealed your office and will be searching it, along with the rest of the embassy.”

  “Searching?” Nagel could feel her only leverage slipping away. “For…what?”

  Kerble ignored the question and turned to Dana. “Ms. Daněk, if you have tendered your resignation, you will need to exit the embassy immediately. Do you understand?”

  “I do…but—”

  “Are those your personal items in that box?”

  Dana nodded.

  Kerble walked over to the box, peered inside, and then glanced back at Nagel, catching her eye for an instant as the other Marines focused on binding her wrists. She watched as Kerble leaned over Dana’s desk and jotted something on a sticky note. Then, in one smooth motion, he reached into his uniform’s breast pocket, extracted the diplomatic pouch Nagel had given him, affixed the sticky note to it, and slid the pouch into the box, tucking it out of sight beneath Dana’s belongings.

  Did he really just do that?!

  Stone-faced, Kerble marched back toward Nagel, who was now restrained with a set of standard-issue nylon flex cuffs. “Madam Ambassador,” he said, “I would suggest you follow the orders of these men without hesitation. It is for your own safety.”

  Before Nagel could reply, Kerble had turned back to Dana.

  “Ms. Daněk!” he said sternly, leaving no doubt who was in charge. “Time’s up—collect your box of personal items and vacate these premises immediately!”

  Dana looked frightened as she grabbed her cardboard box and rushed past the handcuffed ambassador, heading straight for the exit.

  Nagel is in some serious trouble.

  Scott Kerble watched as his officers escorted the ambassador down the service stairwell toward the basement. Having served diplomats his entire career, Kerble had never met one he more admired or trusted than Heide Nagel. His impulsive decision to break ranks and protect her had been a reflex…a gut instinct…and he had done it at no small risk to his career.

  Something is not right here…

  CIA Director Gregory Judd had offered Kerble’s team no details—only a direct order; the ambassador was to be locked in the embassy’s situation room, under guard, and detained until further notice.

  Wildly irregular.

  Stranger still, the director had ordered an exhaustive search of the ambassador’s private office to collect any and all digital media—computers, hard drives, DVDs, USBs, etc.—which made sense in only two scenarios. Either they suspected Nagel was a spy, which was absurd, or the director was afraid she had information that would be damaging to the agency itself.

  Kerble felt confident that whatever the director was hoping to confiscate had just left the building…in a cardboard box with Dana Daněk.

  Keep it safe, the ambassador had told him. Mention it to no one.

  Kerble had no idea what the contents of the pouch might be, but he knew Dana would never dare open it. Moreover, the CIA director would be the last person Dana would ever call about it.

  Just to be certain, Kerble had added a safely anonymous sticky note to the pouch:

  D— Tell no one about this. Someone will contact you.

  The pouch is safe, he thought. At least for the moment.

  Kerble had said nothing to his colleagues. Nor had he mentioned the ambassador’s aberrant behavior—including her arrival to the embassy on foot and unescorted. Nagel is the most ethical person I’ve ever met, he reminded himself. She’s clearly caught up in something I don’t understand.

  Considering the ambassador was now in custody, he thought it prudent to recover her private SUV, get it off the street, and store it in the embassy’s parking courtyard with the rest of the fleet. Kerble went to the security office and retrieved the emergency set of keys they kept for all embassy vehicles. Then he turned to a computer terminal to pull up the location of the concealed tracking device that existed in any vehicle that might carry the ambassador. Kerble knew the SUV was close by, since the ambassador had walked back to the residence, but using the GPS coordinates would save him precious time wandering the streets.