Matt let out a slow sigh of relief. They had survived Arrigetch.

Then movement in the tarn’s reflection caught his eye.

Another plane.

The Cessna shot into the cirque, entering from an entirely different direction. From the way the plane bobbled for a moment, Matt guessed their pursuers were just as surprised to see them here.

“Jen?” Matt said.

“I don’t have enough altitude yet to clear the cliffs.” Her words for the first time sounded scared.

The two planes now circled the stone amphitheater, climbing higher, the tense pageant mirrored in the blue lake below. The door to the other plane shoved open. From seventy yards away, Matt spotted the now familiar parka-clad figure brace himself in place, shouldering the grenade launcher.

He turned back to Jenny. He knew he’d eventually regret his next words, but he also knew they would never clear the top of the cliffs before they were fired upon. “Get us back into Arrigetch!”

“There’s not enough time!”

“Just do it.” Matt unbuckled and climbed from the copilot seat. He scrambled over to the side window that faced the other plane.

Jenny banked toward the maze of rock, circling back toward Arrigetch.

Matt unhitched the window and slid it back. Winds blasted into the cabin. Bane barked excitedly from the backseat, tail wagging furiously. The wolf loved flying.

“What are you doing?” Jenny called to him.

“You fly,” he yelled, and cracked open the emergency box by the door. He needed a weapon, and he didn’t have time to free and load the shotgun. He grabbed the flare gun inside the emergency kit and jammed it out the window. He pointed it at the other plane. With the winds, prop wash, and shifting positions of the planes, it was a Hail Mary shot.

He aimed as best he could and pulled the trigger.

The fizzling trail of the flare arced across the cirque, reflected in the tarn below. He had been aiming for the parka-clad figure, but the winds carried the flare to the side. It exploded into brilliance as it sailed past the nose of the plane.

The other pilot, clearly tense from his transit through the jagged clutches of Arrigetch, veered off, pitching the plane suddenly to the side. The parka-clad figure at the plane’s door lost his footing and tumbled out, arms cartwheeling. But a couple yards down, he snagged, tethered in place to the frame of the door. He swung back and forth under the belly of the Cessna.

It had to be distraction enough.

“Go!” Matt yelled, and slammed the window shut. He crawled back to the front seat.

Jenny’s father patted him on the shoulder as he passed. “Good shot.”

Matt nodded to Craig. “It was his idea.” He remembered the reporter pulling the flare gun on him when he came to his rescue a couple days ago. It had reminded him of a lesson taught to him by his old sergeant: Use whatever you have on hand…never give up the fight.

Feeling better, Matt buckled into place.

Jenny was already diving back into the maze. “They’re coming after us,” she said.

Matt jerked around, surprised. He turned in time to see the flailing man cut free. His form tumbled through the air and splashed into the blue tarn.

Stunned, Matt sat back around. They had sacrificed their own man to continue the pursuit.

Jenny swung the plane over on one wing and sped away among the cliffs. But this time, they couldn’t shake the other plane.

And Jenny was tiring. Matt saw how her hands had begun to tremble. Her eyes had lost their steady determination and shone with desperation. A single mistake and they were dead.

As he thought it, it happened.

Jenny banked hard around a craggy column.

Ahead a solid wall of stone filled the world.

A dead end.

They could not turn away in time. Matt braced himself, expecting Jenny to try, but instead she throttled up.

Matt’s throat closed tight. He suddenly realized where they were and what she was about to attempt. “No, no, no…”

“Oh yes,” she answered him. The nose of the plane dropped sickeningly. She spiraled out a bit and back around.

At the base of the cliff, a river flowed out. Eons ago, an earthquake had rattled Arrigetch, toppling one peak against another. This created a Devil’s Pass, a breach left under the two tumbled peaks.

It was one of the exits from Arrigetch.

Jenny dove toward the river, aiming for the opening in the rock. Her angle was too steep. But at the last moment, she pulled hard on the wheel and throttled down, almost stalling the props. The Otter leveled out a foot above the stream, then shot into the Devil’s Pass.

Instantly the world went dark, and the dull roar of their engines trebled — but daylight lay directly ahead. It was a straight passage, no longer than forty yards. But it was also tight, leaving only a yard to either side.

Jenny was humming again.

“They’re still behind us!” Craig called out.

Matt turned as the Cessna ducked into the tunnel. The other pilot was determined not to lose his target.

Matt clenched a fist. Their last desperate maneuver had been for nothing. The other pilot matched Jenny trick for trick. It was hopeless. Beyond the tunnel lay the open mountains. There would be nowhere to hide.

“Hold tight, folks,” Jenny warned as they neared the far end of the tunnel.

“What are you—?”

Jenny shoved the wheel. The plane dipped. The floats struck the stream hard and skidded over its surface, casting a flume of water behind them. As the plane bounced back up, they were out of the tunnel and sailing high into the air.

Matt searched behind them as Jenny banked away.

From the tunnel mouth, the Cessna appeared, tumbling out, rolling end over end, wings broken. One of the propellers bounced free and spun up the snowy slope.

Matt turned back to his ex-wife with awe. The sudden backwash from her bounce against the stream had struck the other plane’s props and wings, causing the Cessna to bobble and brush against one of the tunnel walls.

A fatal mistake.

Jenny’s voice trembled. “I hate tailgaters.”

It was like stepping into a different world. The Crawl Space outside the Russian ice station was a natural warren of ice caverns and chutes. As Amanda passed over the threshold, she left not only the warmth of the station behind, but also all man-made structures.

Just outside the double doors to the base lay rusty piles of plate steel, bags of old concrete, stacks of conduit, and spools of wire. When it was first discovered, it was assumed the natural space in the ice was used as a storage annex, hence its nickname.

A structural engineer with the NASA group hypothesized that the station may have been constructed within a natural cavern inside the ice island, requiring less excavation. He suggested the Crawl Space might be the tiny remnant of the larger cavern system.

But outside such idle speculation, the Crawl Space held little fascination for most of Omega’s scientists. To them, it was just the janitor’s closet of the base. Only the geologists and glaciologists seemed truly fascinated by these back rooms and ice chutes.

“This way,” Dr. Ogden said, zipping his jacket up to his chin and pulling the fur-lined hood over his bald head. The biologist grabbed a flashlight from a stack near the door, flicked it on, and aimed past the cluttered entrance hall to the dark passages beyond. When he stood a moment longer, Amanda thought he might be speaking to her, but with his back turned, she couldn’t tell for sure. Before she could ask, he set off down toward the warren of tunnels.

Amanda followed. At least the geologists had spread sand on the ice floor for better footing. As she continued, leaving the lighted entrance behind, the air grew much colder. For some reason the motionless air seemed icier than on the surface. She lifted her warming mask from the belt of her thermal suit and flicked on the switch.