The production target of one thousand skyships had been achieved with some to spare, thanks to the driving ruthlessness and Leddravohr and Chakkell.

Fifty of the ships had been set aside for the transportation of the country’s royalty and aristocrats in small family groups who would travel in comparative luxury, though by no means all of the nobility had decided to take part in the migration. Another two-hundred were designated as cargo vessels which would carry food, livestock, seeds, weapons and essential machinery and materials; and a further hundred were for the use of military personnel. That left six-hundred-and-fifty ships which, with reduced two-man crews, had the capability of transporting almost twelve thousand of the general population to Overland.

At an early stage of the great undertaking King Prad had decreed that emigration would be on a purely voluntary basis, with equal numbers of males and females, and that fixed proportions of the available places would be allocated to men with key skills.

For a long time the hard-headed citizenry had declined to take the proposal seriously, regarding it as a diversion, a regal folly to be chuckled over in taverns. The small numbers who put their names forward were treated with derision, and it seemed that if the skyship fleet were ever to befitted it would only be at swordpoint.

Prad had chosen to bide his time, knowing in advance that greater forces than he could ever muster were on the move. The ptertha plague, famine and the abrupt crumbling of social order had exerted their powerful persuasions, and — in spite of condemnation from the Church — the roster of willing emigrants had swollen. But such was the conservatism of the Kolcorronians and so radical the solution to their problems that a certain degree of reserve still had to be overcome, a lingering feeling that any amount of deprivation and danger on Land was preferable to the near-inevitability of a highly unnatural death in the alien blue reaches of the sky.

Then had come the news that an S.E.S. ship had voyaged more than halfway to Overland and had returned intact.

Within hours every remaining place on the emigration flight had been allocated, and suddenly those who held the necessary warrants were objects of envy and resentment. There was a reversal of public opinion, swift and irrational, and many who had scorned the very notion of fly ing to the sister world began to see themselves as victims of discrimination.

Even the majority who were too apathetic to care much either way about the broad historical issues were disgruntled by stories of wagons loaded with scarce provisions disappearing through the gates of Skyship Quarter…

Against that background Lain had argued that the proving flight had achieved all its major objectives by successfully turning over and passing the midpoint. The descent to the surface of Overland would have been a passive and predictable business; and Zavotle’s sketches of the central continent, viewed through binoculars, were good enough to show that it was remarkably free of mountains and other features which would have jeopardised safe landings.

Even the loss of a crew member had occurred in such a way as to provide a valuable lesson about the inadvisability of cooking in weightless conditions. The commander of the ship was to be congratulated on his conduct of a uniquely demanding mission, Lain had concluded, and the migration itself should begin in the very near future.

His arguments had been accepted.

The first squadron of forty skyships, mainly carrying soldiers and construction workers, was scheduled to depart on Day 80 of the year 2630.

That date was only six days in the future, and as Lain’s steed picked its way up the hill to the cave it came to him that he was curiously unexcited by the prospect of flying to Overland. If all went according to plan he and Gesalla would be on a ship of the tenth squadron, which — allowing for delays caused by unsuitable weather or ptertha activity — was due to leave the home world in perhaps only twenty days’ time. Why was he so little moved by the imminence of what would be the greatest personal adventure of his life, the finest scientific opportunity he could ever conceive, the boldest undertaking in the entire history of mankind?

Was it that he was too timorous even to allow himself to think about the event? Was it that the growing rift with Gesalla — unacknowledged but ever present in his awareness — had severed a spiritual taproot, rendering him emotionally sere and sterile? Or was it a simple failure of the imagination on the part of one who prided himself on his superior qualities of mind?

The torrent of questions and doubts subsided as the bluehorn reached a rock-strewn shelf and Lain saw the entrance to the cave a short distance ahead. Grateful for the internal respite, he dismounted and waited for the soldiers to catch up on him. The four men’s faces were beaded with sweat below their leather helmets, and they were obviously puzzled at having been brought to such a desolate spot.

“You will wait for me here,” Lain said to the burly sergeant. “Where will you post your look-outs?”

The sergeant shaded his eyes from the near-vertical rays of the sun which were stabbing past the fire-limned disk of Overland. “On top of the hill, sir. They should be able to see five or six observation posts from there.”

“Good! I’m going into this cave and I don’t want to be disturbed. Only call me if there is a ptertha warning.”

“Yes, sir.”

While the sergeant dismounted and deployed his men Lain opened the panniers strapped to his bluehorn and took out four oil lanterns. He ignited the wicks with a lens, picked the lanterns up by their glasscord slings and carried them into the cave. The entrance was quite low and as narrow as a single door. For a moment the air was even warmer than in the open, then he was in a region of dim coolness where the walls receded to form a spacious chamber. He set the lanterns on the dirt floor and waited for his eyes to adjust to the poor light.

The cave had been discovered earlier in the year by a surveyor investigating the hill as a possible site for an observation post. Perhaps through genuine enthusiasm, perhaps out of a desire to sample Lord Glo’s noted hospitality, the surveyor had made his way to Greenmount and lodged a description of the cave’s startling contents. The report had reached Lain a short time later and he had decided to view the find for himself as soon as he had time to spare from his work. Now, surrounded by a fading screen of after-images, he understood that his coming to the dark place was symbolic. He was turning towards Land’s past and away from Overland’s future, confessing that he wanted no part of the migration flight or what lay beyond it.…

The pictures on the cave walls were becoming visible.

There was no order to the scenes portrayed. It appeared that the largest and flattest areas had been used first, and that succeeding generations of artists had filled in the intervening spaces with fragmentary scenes, using their ingenuity to incorporate bosses, hollows and cracks as features of their designs.

The result was a labyrinthian montage in which the eye was compelled to wander unceasingly from semi-naked hunters to family groups to stylised brakka trees to strange and familiar animals, erotica, demons, cooking pots, flowers, human skeletons, weapons, suckling babes, geometrical abstracts, fish, snakes, unclassifiable artifacts and impenetrable symbols. In some cases cardinal lines had been graven into the rock and filled with pitch, causing the images to advance on the sight with relentless power; in others there was a spatial ambiguity by which a human or animal form might be defined by nothing more than the changing intensity of a patch of colour. For the most part the pigments were still vivid where they were meant to be vivid, and restrained where the artist had chosen to be subtle, but in some places time itself had contributed to the visual complexity with the stainings of moisture and fungal growths.