The cave’s passageways curved and branched like the interior of some massive, crystalline organism. The temperature had dropped precipitously the deeper they had ventured into the mountain. While their breath still hung in clouds before their faces, it wasn’t as cold as it had been a few hours ago. That had to be a sign that they were nearing the other side of the mountain.

Still, Brook had lost sensation in her toes hours ago. Her thick hiking boots had proved somewhat inadequate against the relentless cold. She flexed the soles of her feet, willing the circulation back while coming to a stop behind Victor.

“Walk,” Victor directed Jacob, his patience at the snapping point.

“Stress is a silent killer, Agent Brall. Isn’t that right, dear sister?”

Victor once again instructed Jacob to keep walking, practically forcing him to select one of the two passageways. Brook had tried multiple times to figure out their route, but the cave’s complex network of tunnels had made it challenging. Despite her brother’s remarkable intelligence, memorizing all the passageways during his stay in Alaska would have been nearly impossible.

While Victor and Jacob entered the tunnel on the right, Brook intentionally hung back. Something about Jacob's whistling had been nagging at her for hours. She had gotten rather adept at learning to recognize behavioral patterns. There were tiny threads of consistency that even the most chaotic personalities couldn't help but weave into their actions.

She mentally retraced their journey, replaying each instance of Jacob's whistling. The first time had been right before they had encountered a fork in the cave system. The second had occurred about thirty seconds before another junction. The third...

The whistling hadn’t been random.

Jacob had deliberately been distracting them this entire time.

Brook’s gaze fixed on her brother's back. He hadn’t memorized the route from exploring the cave.He had marked them. As if sensing a shift in the air, Jacob glanced back at her, his eyes reflecting the light of her headlamp with an almost animal luminescence.

Brook forced herself to move forward, with Russell trailing behind, carrying one of the bags. She held the other, leaving Victor to focus solely on Jacob.

They continued in silence for another twenty minutes. The only sounds were their labored breathing and the crunch of their boots on the icy floor. Brook kept careful count of their turns—left, right, right, left—trying to build a mental map of their progress.

She felt fairly confident that Jacob was steering them clear of the mountain's deepest center. This path was safe for them, considering the risks posed by the frigid temperatures.

Then, like clockwork, Jacob began to whistle again.

Victor's patience snapped.

“Jesus Christ,” Victor muttered in irritation. “Not another sound.”

Jacob obliged, falling silent with that same enigmatic smile. Sure enough, within a minute, they approached another junction—this time a choice between two identical-looking tunnels.

“You really should take up meditation, Agent Brall. I’ve recently applied the practice of mindfulness in my daily routine. Given my current living conditions, you can imagine how useful the technique is for my mental health.” Jacob came to a complete stop, tilting his head to the right as he appeared to consider both passages. “The tunnel on the left, or the tunnel on the right?”

Jacob made a soft tsking sound with his tongue.

“Let’s try the right passageway, shall we?”

Jacob began advancing in the direction he had chosen, with Victor remaining close to his side. Russell, who had been bringing up the rear of their small party, moved to follow. When she stayed still, he frowned at her until she held up a finger to her lips. He hesitated briefly before nodding almost imperceptibly.

“Go ahead,” Brook mouthed, gesturing for him to follow Victor and Jacob so they didn’t question why there weren’t footsteps following in their wake.

As Russell reluctantly moved forward, Brook remained rooted in place, her headlamp trained in the area where Jacob had made his decision. Something wasn't right, and she needed just a moment to figure out what her brother had been doing for the past nine hours without their knowledge.

The beam of her light played across the ice, revealing nothing but smooth, glassy surfaces and the occasional crystalline outcropping. Jacob had been so certain in some cases—first wrong, then right—as if reading from a script only he could see.

Brook examined the walls a little more carefully.

What was he observing that they weren’t?

She finally had to relent this time around when she noticed nothing out of the ordinary. Propelling herself forward, she hurried to catch up before the distance between them grew too great. The sound of her brother's voice echoed back to her through the tunnel, casual and conversational, as if they were taking a stroll through a park rather than navigating an ice cave in an Alaskan mountain.

“Did you know," Jacob was saying to Victor by the time she was able to close the distance, "that ice has memory? Scientists say that if you heat it up and then refreeze it, it remembers its previous crystalline structure.”

“Fascinating,” Victor murmured dryly.

Jacob began to whistle, and soon, they were once again given a choice of two passageways. The ritual wasn’t in her imagination. She motioned for Russell to proceed her a second time, waiting for Jacob and Victor to enter one of the passageways.