The computer took the seating plan of the remaining passengers, computed total maximum survival probability for the group, and slid the rear set of emergency doors out of the fuselage walls and across the width of the cabin. Three crew members were trapped aft of the seal.

Oxygen was released into the forward part of the cabin from the emergency supply. The tough plastic of the emergency doors bellied under the pressure, but it held easily. Four seconds after the explosion, the atmosphere was again able to support life. While the surviving passengers gulped in oxygen and held their ears against the agony of the sudden pressure changes, the computer began Stage Two.

The rear control surfaces were gone. The computer switched off all flight power, jettisoned the self-contained nuclear reactor unit a fraction of a second before the captain could do it, and flashed an estimated landing location to the Search and Rescue System.

The rear braking chute had gone, too. Computed impact speed, even with the deployment of the forward chute, would still be too high. The computer trimmed all surfaces to minimize descent speed. It prepared to deploy the forward chute, and positioned the air-bags to release the instant before ground impact. The craft would hit inland, seven thousand feet above sea level on the polar ice cap. The Search and Rescue Satellite also computed a trajectory and sent back a confirmation of the estimated arrival point. Messages had already gone out to the nearest ground-based Search and Rescue teams, telling them the number of passengers and crew, their ages and physical condition.

There had been no time to think. Julia Merlin and the other passengers lay helplessly back in their seats while the aircraft dropped like a stone through the long day of an Antarctic November. The fall from ninety thousand feet with chute deployed took six minutes; long enough to breathe again, to despair, and finally to hope.

They almost made it. If the impact had been into soft new snow, instead of old and hard-packed ice, the hull would have remained intact. Instead, it split along its length, spilling some of the passengers and fixtures outside onto the hard ice. The air bags absorbed most of the momentum, so the more fortunate passengers found themselves lying dazed but unharmed inside the ruined hull as it slipped and scraped to a halt down the steep ice-slope.

Julia Merlin was one of the unlucky ones. The portion of the craft where she sat was squeezed vertically as the right wing collapsed and the vessel rolled hard over to the right. A metal brace from the cabin roof above her moved down hard, caught her square on the forehead, and thrust her out of her seat through the gaping side of the hull. The plane skidded on. Julia’s body slithered to a halt almost a quarter of a mile short of the place where the ruin of the aircraft stopped its downward career.

Partially shielded by the remains of the air-bag, her body lay supine and bleeding on the ice. The frontal and parietal lobes of her brain had been crushed to a grey and oozing pulp by the impact of the hardened aluminum brace. Her clothing had been ripped from her as she was ejected from the cabin. But she was not dead. The most ancient part of her brain still functioned. Somehow, the process that had begun when she first entered the aircraft continued its work. In the bleak light of the Midnight Sun, the ageless rhythm of parturition quickened in Julia Merlin’s unconscious body.

Soon the head was born, thrusting naked into the light of the long day. For a highland area of the ice cap, the weather might be regarded as mild. The new-born was emerging into an atmosphere that held thirty degrees of frost, with a stiff breeze to carry the effective temperature twenty degrees lower. Julia Merlin’s thighs provided a partial shield, no more.

The Search and Rescue Team had left Porpoise Bay just minutes after the emergency call was received there. They made excellent time flying over to the wreck and they spotted it at once. The first few minutes were spent caring for the passengers who were still inside the hull, then the team fanned out rapidly across the ice, looking for other survivors.

They came to Julia Merlin’s body last of all. Even so, they were almost in time.

The morning sun, moving slowly higher, cast a broad swath of light around the south-east face of K-2. The bright shaft crept along the steep walls of ice and overhanging rock, up to the tiny figure that hung cocoon-like against the rock face. When the light reached his face mask he stirred in his sleeping bag, fumbling for the dark goggles that would protect his eyes against the fierce ultra-violet. After a couple of minutes he pushed his head out of the bag and looked around him. The weather was holding, with no clouds and with tolerable winds. He glanced up. The summit was invisible past the overhang, but it must be less than two thousand feet above him, standing solitary against the blue-black sky.

Rob Merlin pulled his head back into the shelter of the bag and began his slow, methodical preparation for the day’s work, the same procedure that had begun each of the last eleven days. His mind was awake. Now he had to waken his hands. That took fifteen minutes of steady rhythmic exercise, joint by joint and digit by digit, until he was finally satisfied with the coordination. Twenty minutes later he was slipping the clamps loose that held his climbing suit tight to the rock, tucking them into the pack, and beginning a careful ascent. At this height, the appearance of the rock surface was deceptive. Each hand-hold must be carefully tested, each piton placed and checked before any new movement could be made. He had studied the preferred ascent route for so long that the choice of direction and movement had passed below the level of his conscious thoughts. That was dangerous. No amount of prior study could tell of crumbling rocks and moving ice cover. As needed, he made the minor changes to his path, crabbing right and left but always ascending.

By noon he had reached the last, gently-sloping ice field that led to the final summit. He paused there, looking about him at the Karakorum Range. In the clear, thin air, he could see well over a hundred miles. The snow-capped peaks marched endlessly away from him, swelling towards the south-east where Everest stood more than seven hundred miles distant. With his eyes fixed on the jagged peaks he slid down his face mask, loosened the oxygen tube that led from his backpack to the corner of his mouth, and began to eat a cold meal of dry concentrates.

To the south, hovering high in the eye of the noonday sun, a small aircraft hung suspended. It would have been invisible to Rob Merlin, even if he had found reason to squint towards the blinding disc — his photo-sensitive goggles would have darkened too much to see anything but the sun itself. The pilot had placed the craft on automatic control while she fine-tuned the electronic magnifier of the telescope. As she corrected the setting, the figure of Rob Merlin, ant-like in the view-finder, sprang suddenly into sharp focus on the display screen. He was crouched forward, leaning to balance the weight of his backpack. Under the thermal clothing his body appeared stocky and powerfully built, with heavy shoulders and a broad back. The woman watched him in silence as he ate the simple meal.

“He’s on the final approach,” she said at last. “The last piece is no problem, that’s why he stopped to eat here. I don’t think he’ll stay long at the top. He’ll want good light to start the descent, especially that chimney about six hundred meters down. Do you want me to keep the viewer on him?”

There was a pause of several seconds. The voice that finally came from the speaker was rough and gravelly, as though the vocal cords were scarred and roughened.