Faraday pointed toward it. “See? That’s exactly what I mean. A valley glacier like the Fear should taper to a nice, thin ice front, with a minimum of meltwater and a healthy percolation zone. But this one is calving like a tidewater glacier. I’ve been measuring the basal melt-”

“That’s Sully’s job, not yours.”

“-and it’s off the scale.” Faraday shook his head. “Rain, unprecedented melting-and there are other things happening, too. Like the northern lights the last few nights. You notice them?”

“Of course. A single color-it was spectacular. And unusual.”

“Unusual.” Faraday repeated the word thoughtfully.

Marshall did not reply. In his experience, every scientific expedition, even one as small as this, had its Cassandra figure. Wright Faraday-with his prodigious learning, his pessimistic outlook on life, his dark theories and outrageous predictions-played the role expertly. Marshall gave the biologist a covert glance. Despite knowing him casually as a university colleague, and now having spent a month almost continually in his presence, he didn’t really have a good idea what made the man tick.

Still- Marshall thought as he filled and sealed a fresh bag, recorded the sample’s location in a notebook, then measured and photographed the extraction site-Faraday had a point. And that point was one reason he himself was collecting samples at an almost frantic pace. A glacier was a near-perfect place for his kind of research. During its formation, as it accumulated snow, it trapped organic remains: pollen, plant fibers, animal remains. Later, as the glacier retreated, melting slowly away, it gracefully yielded up those secrets once again. This was an ideal gift for a paleoecologist, a treasure trove from the past.

Except there was nothing slow or graceful about this glacier’s retreat. It was falling to pieces with alarming speed-and taking its secrets with it.

As if on cue, there was another ear-shattering explosion from the face of the glacier, another shuddering cascade of ice. Marshall glanced toward the sound, feeling a mixture of irritation and impatience. A much larger section of the glacier’s face had fallen away this time. With a sigh, he bent toward his specimens, then abruptly swiveled back in the direction of the glacier. Among the fractured ice boulders at its base, he could see that part of the mountain face beneath had been exposed by the calving. He squinted at it for a moment. Then he called over to Faraday.

“You’ve got the field glasses, don’t you?”

“Right here.”

Marshall walked toward him. The biologist had pulled the binoculars from a pocket and was holding them out with a heavily gloved hand. Marshall took them, breathed on the eyepieces to warm them, wiped them free of mist, then raised them toward the glacier.

“What is it?” Faraday said, excitement kindling in his voice. “What do you see?”

Marshall licked his lips and stared at what the fallen ice had revealed. “It’s a cave,” he replied.

An hour later, they stood before the icy rubble at the Fear glacier’s front face. The freezing rain had stopped, and a weak sun struggled to pierce the gunmetal clouds. Marshall rubbed his arms briskly, trying to warm himself. He looked around at their little group. Sully had returned, bringing with him Ang Chen, the team’s graduate student. Except for Penny Barbour, their computer scientist, the entire expedition was now assembled at the terminal moraine.

The cave lay directly ahead, its mouth black against the clear blue of the glacial ice. To Marshall, it looked like the barrel of a monstrous gun. Sully stared into it, chewing distractedly on his lower lip.

“Almost a perfect cylinder,” he said.

“It’s undoubtedly a branch pipe,” Faraday said. “Mount Fear’s riddled with them.”

“The base is,” Marshall replied. “But it’s very unusual to see one at this altitude.”

Abruptly, another section of ice front calved off the glacier about half a mile south, collapsing in house-sized blue chunks at its base and throwing up a cloud of ice shards. Chen started violently, and Faraday covered his ears against the roar. Marshall grimaced as he felt the mountain shudder beneath his feet.

It took several minutes for the echoes to die away. At last, Sully grunted. He glanced from the ice face, to the mouth of the cave, to Chen. “Got the video camera?”

Chen nodded and patted the equipment bag slung over one shoulder.

“Fire it up.”

“You’re not planning on going in, are you?” Faraday said.

Instead of answering, Sully straightened to his full five feet six inches, sucking in his paunch and adjusting the hood of his parka, readying himself for the camera lens.

“It’s not a good idea,” Faraday went on. “You know how brittle the lava formations are.”

“That’s not all,” Marshall said. “Didn’t you see what just happened? More ice could calve off and bury the entrance at any minute.”

Sully looked back at the cave indecisively. “They’d want us to.”

“They” referred to Terra Prime, the cable channel devoted to science and nature that was underwriting the expedition.

Sully rubbed one gloved hand against his chin. “Evan, Wright, you can stay out here. Ang will follow me in with the camera. If anything happens, get the army guys to chop us out.”

“The hell with that,” Marshall said immediately, grinning. “If you discover buried treasure, I want a cut.”

“You said it yourself. It’s not safe.”

“All the more reason you need another hand,” Marshall replied.

Sully’s lower lip protruded truculently, and Marshall waited him out. Then the climatologist relented. “Okay. Wright, we’ll be as quick as we can.”

Faraday blinked his watery blue eyes but remained silent.

Sully brushed stray flakes of snow from his parka, cleared his throat. He glanced up a little gingerly at the ice front. Then he positioned himself before the camera. “We’re standing at the face of the glacier,” he said in a hushed, melodramatic voice. “The retreating ice has exposed a cave, nestled in the flank of the mountain. We’re preparing to explore it now.” He paused dramatically, then signaled for Chen to stop recording.

“Did you really say ‘nestled’ just now?” Marshall asked.

Sully ignored this. “Let’s go.” He pulled a large flashlight out of his parka pocket. “Ang, train the camera on me as we go inside.”

He started forward, the gangly Chen obediently following in his wake. After a moment, Marshall pulled out his own flashlight and swung in behind them.

They picked their way slowly and carefully through the debris field. A few of the blocks of ice were the size of a fist; others, the size of a dormitory. In the weak sunlight, they glowed the pale blue of an October sky. Runnels of meltwater trickled past. As the three continued, the shadow of the glacier fell over them. Marshall looked up apprehensively at the vast wall of ice but said nothing.

Close up, the cave mouth looked even blacker. It exhaled a chill breath that pinched at Marshall ’s half-frozen nose. As Sully had said, it was quite round: the typical secondary vent of a dead volcano. The glacier had smoothed the surrounding rock face to almost a mirror finish. Sully poked at the blackness with his flashlight. Then he turned toward Chen. “Turn that off a moment.”

“Okay.” The student lowered the camera.

Sully paused, then glanced at Marshall. “Faraday wasn’t joking. This whole mountain is one big pile of fractured lava. Keep on the lookout for any weaknesses. If the tube seems at all unstable, we turn back immediately.”

He looked back at Chen, nodded for him to start filming again. “We’re going in,” he intoned for the camera’s benefit. Then he turned and stepped into the cave.

The roof wasn’t especially low-at least ten feet-yet Marshall ducked instinctively as he followed Chen inside. The cave bored straight into the mountain, descending at a gentle grade. They proceeded cautiously, flashlight beams playing over the lava walls. It was even colder in here than out on the ice field, and Marshall snugged the hood of his parka tightly around his face.