CHAPTER ELEVEN
The elevator to the sublevel was a different one from the others that had taken them to the fourth and fifth floors so far this morning.
This elevator was smaller, more compact, and very quiet.
The change in mood and setting hit as soon as the doors slid apart.
The air was several degrees cooler, and the light shifted from the warm white of the upper floors to something bluer, almost clinical.
"Blade Runner," Novak said, looking down the hallway. "That's the only way I can describe it."
Rachel, only barely familiar with the movie, nodded.
The corridor was narrow and lined with black paneling instead of the glass and stone upstairs.
Server racks hummed behind a glass wall to their left, rows of blinking lights stacked floor to ceiling.
A handful of workstations sat in an open area further down.
Most of them were empty, their monitors glowing with scrolling code nobody was currently reading.
They walked ahead and found a man hunched over a workstation. He looked up as they came by, looking confused.
“Can I help you?” he asked, eyeing the access cards on the lanyards around their necks.
“Yes, we’re looking for Dr. Kline.”
“Oh, she’s in Lab 2A. Keep walking back and it’s the first lab on the right.”
They followed these instructions and, just ten seconds later, found Kline in an open-walled lab.
She was positioned behind a standing desk; three monitors were arranged in a shallow arc in front of her, each one filled with graphs and a streaming series of numbers.
Kline turned when Rachel knocked on the thin frame of the entryway.
"Agents! Dr. Sloan just rang to let me know you were coming.”
Of course he did, Rachel thought.
Kline waved them in and gestured at two chairs pulled up near the desk. They were plain and utilitarian compared to the furniture upstairs. She clapped her hands twice, excitedly and smiled widely at them. “So you need to know about the model, right?”
Taken slightly aback at Kline’s energetic personality, Rachel could only nod. Because honestly, once the technical jargon got too complicated, she wasn’t sure what in the hell they needed to hear about.
“Yes, please,” Novak said. Apparently, he was in the same boat.
"I have to say, I've been hoping somebody would ask me about the model directly instead of just asking Nina to explain it secondhand."
"We'd like that," Rachel said, sitting. "Can you walk us through how it actually works? Not the marketing version."
Kline's face lit up in a way that made her look younger than she probably was.
"Finally. Okay." She turned one of the monitors toward them, pulling up a chart with a curve rising and then gently bending downward.
"This is a composite health trajectory. Every user gets one of these, built off dozens of individual inputs.
Resting heart rate variability, VO2 max, sleep architecture, recovery windows, even grip tremor.
We don't just track where those numbers are.
We track the rate of change in each one over time. "
"And that gives you the peak date," Novak said.
"Right. Well, mostly. See, it's not one input predicting one date.
It's a convergence model." Kline pulled up a second graph layered with multiple colored lines.
"Imagine six or seven different curves, each one representing a different biological system, each one rising and eventually declining at its own pace.
The peak isn't when any single line is at its highest point.
It's the moment where the combined slopes cross a threshold where the whole system is operating at maximum efficiency, all at once.
After that point, one or more of those systems start to decline faster than the others compensate for. "
"How far in advance can you predict it?" Rachel asked.
"For a user who's been wearing the device consistently for at least a year, we can usually narrow it down to a window of about ten days…
about eight to twelve weeks out. As we get closer, the model recalibrates weekly, and the window tightens.
By the final month, we're often within two or three days.
" Kline said this with no hesitation, no attempt to soften it.
"It's genuinely one of the best predictive models of its kind.
I built most of the recalibration logic myself. "
"You sound proud of it," Novak said.
"I am proud of it," Kline said simply. "It's good work. I don't think there's anything wrong with saying that. As a matter of fact, I’ve turned down ridiculous offers for the secrets and to jump ship to other teams.”
Rachel let her explain a little further, watching the way Kline moved between the monitors.
She pulled up sample datasets and narrated the mechanics behind each one without being asked to do so.
There was nothing evasive in it, none of the careful phrasing Oakley had used or the philosophical hedging Sloan had leaned on.
She answered as if the questions themselves were satisfying.
Rachel got the very real sense that Kline would be more than happy to speak with them for hours about this if her schedule allowed for it.
"Can I ask you something else?" Rachel said once Kline had paused. "Something about the team, not the algorithm."
"Sure."
"How many people work on this model with you?"
"Eight of us total on the model team, including me." Kline shrugged. "Data scientists, a couple of ML engineers, one statistician who mostly checks our work. We’re a small group, but tight-knit."
"How would you describe the mental health of your team?" Rachel asked. "Any concerns, past or present? Anyone who's struggled, taken leave, anything like that?"
Kline laughed, a short surprised sound. "You're asking if one of my engineers is secretly murdering people."
"No. I'm asking about your team's mental health," Rachel said, keeping her tone level. She didn’t bother asking how she knew they were here discussing murders. She thought it was a very safe assumption that Sloan had told her during their brief call.
Kline looked at her for a second longer, waiting for the joke to reveal itself, and when it didn't, something in her face shifted. The easy warmth from a moment earlier folded into something tighter.
"You're serious," she said.
"I am."
"That's..." Kline sat back slightly, arms crossing.
"That's insulting, honestly. These are some of the most careful, disciplined people I've ever worked with.
We built something that's actually helping people, and now you're sitting in my office asking if one of them is a killer because they happen to understand the math. "
"I'm not accusing anyone," Rachel said. "Two people are dead on the exact days your model predicted. We have to ask the question. Surely you can understand that."
Kline's jaw tightened, and for a moment she didn't say anything. She just looked between Rachel and Novak like she was recalculating something. When she spoke again, her voice had lost the enthusiasm and spunk she’d been using so far. It had been replaced by something flatter and more formal.
"Fine," she said. "You want to know who has access to individual predictions, and whether anyone on my team has been pulling that data. Right?”
“Yes,” Novak snapped.
“Yeah, okay. I'll go through the export logs myself. Every access request, every download, every query against the model going back as far as the system retains it."
"We'd appreciate that," Rachel said.
"I'm not doing it because I think you're right." Kline's voice had an edge to it now. "I'm doing it because I want this cleared up and away from the press. If there's a leak somewhere in my system, I want to be the one who finds it, not some outside auditor Sloan brings in to make a show of it."
"That's fair," Novak said.
"I'll have something for you by tomorrow.
" Kline turned back to her monitors, effectively signaling that the conversation was over, though she added one more thing before they reached the door.
"Whoever did this, if it really is somebody with access, they didn't get it from sloppy security. I built that system tight. Somebody worked to get around it. Now, if that’s all…”
“It is,” Rachel said. “For now. Thank you.”
They left the lab area and headed back for the elevator. They rode back up and when the doors opened, the sublevel's cool blue light gave way to the warmer glow of the lobby.
"She went from thrilled to furious in about four seconds," Novak said.
"She wasn't expecting such a to-the-point question," Rachel said. "Nobody likes being asked if the people they trust the most might be capable of something like this."
"You think she'll actually pull those logs?"
"I think she will, because she wants to be the one who finds the answer before anyone else does. And, like she said, she’d like to keep it away from the media.
I think right now, she’s probably the most reliable asset we have.
" Rachel pulled out her phone as they crossed the lobby.
"But I want more than her logs. I want Sloan's employee files.
Every person who's worked on that model team, past and present, anyone who left under bad circumstances. "
"You think Tanner's leak and our killer are connected?"
"I think it's worth asking," she said. "Pulling an individual peak date without tripping whatever Kline's got watching that system, that's not something just anyone on the team could do.
Somebody figured out how to get in and out clean, for a year, without her catching it until we showed up asking. "
"Right,” Novak said. “Tanner's source just wanted the dates as proof. The killer needed it before Pike or Mott posted it themselves. That's tighter. Somebody built a way in, or they're the one feeding Tanner and using him without him knowing it."
"So either it's the same person doing both," Rachel said, "or two people found two different uses for the same hole in the system."
"Either way,” Novak said as they headed out to the parking lot, “it's somebody who knows that model well enough to move through it without leaving anything Kline's already found. And if we can get those employee records, maybe the answer is just waiting there.”
Rachel nodded and grinned as she headed back to the lobby’s front desk. “And I think we may get those records without much hassle,” she said. “It seems they’re really starting to get tired of us.”