"Another three or four miles to go. We should be there in twenty minutes."

"Are you going to crash the party unannounced?"

"Not a wise move against an army of security guards," answered Pitt. "That low rock ridge protruding from the ice that angles toward the base of the mountains?"

"I see it."

"We can run along out of sight of the compound, using it for cover while we close the final two miles."

"We just might make it," said Giordino, "if they don't spot our exhaust."

"Keep your fingers crossed," Pitt said with a tight grin.

They left the great ice plain of the Ross Ice Shelf and crossed onto ice-mantled land and skirted the ridge that trailed down from the mountain like a giant tongue, keeping below the summit out of sight of the mining compound as they crept ever closer. Soon they were driving beneath towering gray rock cliffs, with streams of ice hanging from their crests like frozen waterfalls, gleaming blue-green under the radiant sun. The path they took along the base of the mountains was not flat or smooth but strewn with wavelike undulations.

Pitt downshifted the Snow Cruiser into second gear to climb the series of low mounds and valleys. The burly machine took the uneven terrain in stride, her wide wheels moving the great ma.s.s up and down the grades without effort. His eyes swept the instrument panel for the tenth time in as many minutes. The temperature gauges indicated that the slow speeds at high rpms were causing the diesels to overheat again, but this time they could keep the door open without suffering the agonies of a blizzard.

They were pa.s.sing the mouth of a narrow box canyon when Pitt suddenly stopped the Snow Cruiser.

"What's up?" Giordino asked, staring at Pitt. "You see something?"

Pitt pointed downward through the windshield. "Tracks in the snow leading into the canyon. They could have only been made by the treads from a big Sno-cat."

Giordino's eyes followed Pitt's outstretched finger. "You've got good eyes. The tracks are barely visible."

"The blizzard should have covered them," said Pitt. "But they still show because the vehicle that made them must have pa.s.sed through just as the storm was ending."

"Why would a Sno-cat travel up a dead-end ravine?"

"Another entrance to the mining compound?"

"Could very well be."

"Shall we find out?"

Giordino grinned. "I'm dying of curiosity."

Pitt cranked the steering wheel to its stop and sharply turned the Snow Cruiser into the canyon. The cliffs rose ominously above the ravine, their height escalating until the sun's light paled the deeper they drove into the mountain. Fortunately, the twists and turns were not severe, and the Snow Cruiser was able to deftly navigate her bulk around and through them. Pitt's only worry was that they'd find nothing but a rock wall, and then have to back the vehicle through the canyon, since there was no room to turn her around. A quarter of a mile from the canyon's mouth, Pitt braked the vehicle to a stop before a solid wall of ice.

It was a dead end. Disillusionment circled their minds.

They both stepped down from the Snow Cruiser and stared at the vertical sheet of ice. Pitt peered down at the tracks that traveled up the canyon and stopped at the wall. "The plot thickens. The Sno-cat could not have backed out of here."

"Certainly not without making a second set of tracks," observed Giordino.

Pitt moved until his face was inches from the ice, cupped his hands around his eyes to block out the light, and stared. He could make out vague shadows beyond the ice barrier. "Something is in there," he said.

Giordino gazed into the ice and nodded. "Is this where somebody says, 'Open Sesame'?"

"No doubt the wrong code," Pitt said pensively.

"It has to be a good three feet thick."

"Are you thinking what I'm thinking?"

Giordino nodded. "I'll stay on the ground outside and cover you with my Bushmaster."

Pitt climbed back into the Snow Cruiser, shifted the gear lever into reverse, and sent the vehicle back about fifty feet, keeping the tires in the packed depressions made by the Sno-cat for better traction. He paused, grasped the wheel tightly in both hands, and burrowed down in the seat, in case the ice should crash through the windshield. Then he shifted into first and jammed the accelerator pedal flat against the floor-boards. With a roar from its exhaust, the big mechanical goliath leaped forward, gathered speed, and then smashed into the frozen wall, rumbling the ground beneath Giordino's feet.

The ice exploded and shattered into a great splash of glittering fragments that showered over the red Snow Cruiser like so many gla.s.s shards from a fallen crystal chandelier. The sound of the impact came like a giant gnashing his teeth. At first, Giordino thought the vehicle might have to ram the thick, solidified ice wall several times before breaking through, but he was almost left behind as it bulldozed its way through on the first try and disappeared on the other side. He chased after it, gun cradled in his arms, like an infantryman following a tank for cover.

Once through, Pitt brought the Snow Cruiser to a halt and brushed the gla.s.s from his face and chest. A large block of ice had burst through the center windshield, narrowly missing him before it fell to the floor and shattered. His face was cut on one cheek and across the forehead. Neither gash was deep enough to require st.i.tches, but the blood that flowed made him look as though he were badly injured. He wiped the crimson from his eyes onto his sleeve and looked to see where the Snow Cruiser had come to rest.

They were sitting inside a large-diameter ice tunnel, with the vehicle's front end firmly embedded in a frozen wall opposite the shattered entry. In both directions the tunnel looked deserted. Seeing no sign of hostility, Giordino rushed into the Snow Cruiser and climbed the ladder to the control cabin. He found Pitt smiling hideously through a mask of blood.

"You look bad," he said, attempting to help Pitt from the driver's seat.

Pitt gently pushed him away. "It's not nearly as bad as it looks. We can't afford time for a clinical repair. You can patch me up with that old first-aid kit in the crew cabin. In the meantime, I vote we follow the tunnel toward the left. Unless I miss my guess, that will lead us to the mining compound."

Giordino knew it was senseless to contest the issue. He dropped down to the crew cabin and returned with a first-aid kit that hadn't been opened since 1940. He cleaned away the congealing blood on Pitt's face, then smeared the cuts with the antiseptic of the era, iodine, whose sharp sting had Pitt cursing in no quiet tones. Then he dressed the skin cuts. "Another life saved by the capable hands of Dr. Giordino, surgeon of the Antarctic."

Pitt looked into the face that was reflected in a side-view mirror. There was enough gauze and tape to cover a brain transplant. "What did you do?" he asked sourly. "I look like a mummy."

Giordino feigned a hurt look. "Aesthetics is not one of my strong points."

"Neither is medicine."

Pitt gunned the engines and maneuvered the hulking vehicle back and forth until he was able to straighten it around for a journey through the tunnel. For the first time, he wound down his window and studied the width of the tunnel. He figured the clearance between the ice and the vehicle's wheel hubs and its roof was no more than eighteen inches. He turned his attention to a large round pipe that ran along the outer arc of the tunnel, with small tubes running vertically from its core into the ice.

"What do you make of that?" he said, pointing to the pipe.

Giordino stepped from the Snow Cruiser, squeezed himself between the front tire and the pipe, and laid his hands on it. "Not an electrical conduit," he announced. "It must serve another purpose."

"If it's what I think it is ..." Pitt's voice dropped portentously.

"Part of the mechanism to break loose the ice shelf," said Giordino, finishing his friend's train of thought.

Pitt stuck his head out his window and stared back into the long tunnel that stretched away to a vanishing point. "It must extend from the mining compound fourteen hundred miles to the opposite end of the ice shelf."

"An inconceivable feat of engineering to bore a tunnel that was equal to the distance between San Francisco and Phoenix."

"Inconceivable or not," said Pitt, "the Wolfs did it. You must remember, it's much easier to bore a tunnel through ice than hard rock."

"What if we cut a gap in the line and stop whatever activation system they've created to split off the ice shelf?" asked Giordino.

"A break might trigger it prematurely," answered Pitt. "We can't take the chance unless we find ourselves left with no other alternative. Only then can we risk dividing the line."

The tunnel looked like a great gaping black mouth. Except for the dim glow of the sun through the thick ice, there was no illumination. An electrical conduit with halogen bulbs s.p.a.ced every twenty feet ran along the ceiling, but the power must have been shut down at the main junction box, because the lights were dark. Pitt turned on the two small headlights mounted on the lower front end of the Snow Cruiser, engaged gears, and drove off, increasing his speed through the tunnel until they were moving at twenty-five miles an hour. Though it was a pace easily sustained by a bicycle rider, it seemed a breakneck speed through the narrow confines of the tunnel.