But they were already descending, their flashlight beams bouncing off damp concrete walls as the temperature climbed with each step down. Isla counted thirty-two stairs before they reached the bottom, emerging into a passage that was narrower than the ones she'd seen at the previous crime scenes. The ceiling hung low enough that James had to duck slightly, and the heat was immediately oppressive despite the December cold they'd left at the surface.
"Jesus," James muttered, already sweating. "How hot does this get?"
Isla consulted Garrett's map on her phone, though the screen was difficult to read in the darkness. "He noted that Junction D-11 reaches 105 degrees. But this corridor should be cooler—maybe eighty or ninety."
Should be. But the air felt wrong, too hot for a passage that supposedly wasn't at the network's thermal center. Isla played her flashlight beam across the walls, noting pipes that radiated heat even through their deteriorating insulation. Someone had been modifying the system, redirecting steam flow, creating conditions that shouldn't exist in this section.
They moved forward in silence punctuated only by their breathing and the distant sound of water dripping somewhere in the darkness. The passage branched at irregular intervals, and Isla checked Garrett's map at each junction, trying to matchthe hand-drawn schematics to the reality of rusted pipes and crumbling concrete around them.
"This way," she whispered, pointing down a corridor that sloped gradually downward. According to Garrett's notes, Junction D-11 was at the lowest point of this sector, a natural collection point for heat that had once been deliberately avoided by maintenance workers but now served as the perfect isolated death trap.
The temperature climbed steadily as they descended. Isla's borrowed winter coat became stifling, then unbearable, and she stripped it off, letting it fall to the damp concrete floor. Sweat ran down her spine, soaked through her shirt, made her weapon grip slippery in her hand. Beside her, James was breathing heavily, his face flushed in the flashlight beam.
"This is insane," he managed. "Nobody could survive down here for long without—"
He stopped abruptly, his flashlight beam catching something ahead in the darkness. A figure, standing motionless at what appeared to be a junction where multiple passages converged.
Thomas Garrett turned slowly toward their light, his weathered face eerily calm in the harsh illumination. He wore what looked like a heavy-duty heat suit, the kind designed for working near blast furnaces or industrial kilns—silver reflective material that covered him from neck to boots, with a hood pushed back to reveal his gray hair matted with sweat.
"Agent Rivers," he said, his voice carrying easily in the enclosed space despite the ambient sound of steam hissing through pipes. "I was wondering when you'd figure it out."
Isla raised her weapon, though her hands were slick with sweat that made her grip uncertain. "FBI. Put your hands where I can see them."
Garrett complied with unsettling calm, lifting his hands slowly to shoulder height. But his expression held no fear, noconcern, just a kind of weary resignation mixed with something that looked almost like satisfaction.
"You're too late," he said simply. "Stacy Lang is already in the chamber. The temperature's been climbing for eleven minutes. She's probably unconscious by now—hyperthermia sets in quickly once core temperature passes 104 degrees. Another three or four minutes and her brain will cook past the point of recovery."
The casual medical terminology, delivered in the same tone he might use to discuss pipe specifications, made Isla's stomach clench. But she forced herself to stay focused, to not let horror overwhelm tactics.
"Where is she?" Isla demanded, moving closer while keeping her weapon trained on Garrett's center mass. "Where's the chamber?"
Garrett nodded toward a steel door behind him, barely visible in the shadows. "Right there. But you can't open it from the outside—I modified the locks. And even if you could, the heat inside would drop you in seconds without protective gear." He gestured to his silver suit. "Which I'm guessing you don't have."
James was already on his radio, calling for emergency response and medical personnel, his voice tight with urgency. But Isla's mind was racing through the layout she'd memorized from Garrett's maps, trying to visualize the junction's configuration, the steam lines that fed it, the controls that would regulate temperature.
"We need to split up," she said quietly to James, her eyes never leaving Garrett. "The temperature controls for this section should be accessible from the junction box—" she gestured vaguely toward where she remembered seeing it marked on the schematics "—but I need you to keep Garrett contained while I find them."
"No," James said flatly. "We stay together."
But Isla was already moving, darting past Garrett toward the shadowed area where the junction box should be located. She heard James shout, heard Garrett say something in that same unsettlingly calm tone, but she couldn't process the words over the roaring in her ears that might have been blood pressure or might have been steam escaping from damaged pipes.
Behind her, she heard sounds of struggle—James confronting Garrett, keeping him away from her while she searched for controls that could save Stacy Lang's life. The flashlight beam bounced wildly as Isla ran, the heat intensifying with every step until breathing felt like inhaling fire.
And there—mounted on the wall near a cluster of pipes that radiated heat like physical pressure—she found the junction box Garrett had marked on his maps. The access panel hung open, revealing modifications to the wiring that looked both sophisticated and terrifying in their deliberate complexity.
Isla holstered her weapon with shaking hands and reached for the controls, praying she understood enough about the system to reverse what Garrett had done, to cool the chamber before Stacy Lang's brain cooked past the point of recovery.
Behind her, in the darkness, she heard Garrett's voice rising above the sound of struggle: "You can't save her, Agent Rivers. Her soul is cold. She needs correction. They all needed correction."
But Isla's fingers were already working at the wiring, trying to undo modifications she barely understood, racing against a clock that measured itself in brain death and cardiac arrest and the absolute failure of human biology when pushed past its thermal limits.
Somewhere in the chamber behind that sealed steel door, a woman was dying.
And Isla had maybe three minutes to save her.
CHAPTER TWENTY-THREE
The junction box wiring was a nightmare of modifications—color-coded cables spliced into configurations that made no sense according to any standard electrical schematic Isla had ever studied. Her hands shook as she traced connections, sweat dripping from her forehead onto the exposed circuits, trying to identify which lines controlled temperature regulation versus which would simply shut down the entire system.
