We're at an indeterminate time in the future. The world of the past eventually died in the conflagration toward which it had been doggedly heading. A more fragmented and diversified order of things has taken shape out of the ruins. While races and remnants of recognizable cultures remain, the former nations and global institutions with their pressures toward conformity have gone. Without a universal stimulus, technology has reestablished itself in some places but not in others. History is not always reconstructed in the way we know it.
While some parts of Earth are ruled as militarized kingdoms suggestive of the European Middle Ages, and others have barely rediscovered the rudiments of industrialization, the region known as Sofi has attained a sophistication in science and technology that in many ways suprpasses anything achieved in the old world. However, the very differences that make Sofi unique lead to a political schism between those who see its superiority as a opportunity to impose its own form of order globally while the rest of the world is powerless to resist, and an opposing faction who see precisely this kind of ambition as the root cause of everything that destroyed the old world. Convinced that the seeds which will eventually make such a course inevitable once again are too deeply embedded in Earth's history and culture to be changed, a movement within Sofi musters sufficient power and access to resources to organize its own solution in the form of a generation mission called Aurora, to found a new human society from fresh beginnings at another star.
The planning of the Aurora program throws up many disagreements. On the question of recruitment, the policy that finally prevails is to aim at a wide variation of backgrounds, talents, and occupations from a broad geographical spread to preserve as far as is practicable the diversity of human culture. The first part of the story follows the experiences of a traveling magician and illusionist called Korshak, from the feudal territories of central and eastern Asia. A chance encounter with a remote-controlled Sofian reconnaissance lander puts Korshak in communication with the Sofian operators and leads to his subsequent recruitment for the mission. But Korshak has fallen for Vaydien, the daughter of a tyrannical ruler, who has pledged her to be married to a vain and cruel prince who is heir to a neighboring petty state. Korshak creates one of his most elaborate illusions to sprit her away during a performance inside the palace itself, under the eyes of her father, the prince, and an audience of courtiers, officials, and military officers, after which he and the group accompanying him are airlifted by the Sofians to join the orbiting Aurora.
The second part of the book takes place eleven years out from Earth, by which time the original ship has begun proliferating into a tiny flotilla of mini-worlds alone in the vastness of interstellar space. Korshak and Vaydien are married with a ten-year-old son and a new daughter, and various people that they met at the time of being brought to Sofi and joining the mission are settled into their new lives. Among these is Masumichi Shikoba, a specialist in machine intelligence and robotics. One of Masumichi's robots played a key part years ago in enabling Korshak and his party to escape their pursuers after disappearing from the palace, and getting them to Sofi in time for the Aurora's departure. Now, a more advanced model of robot has vanished, and Masumichi approaches Korshak to seek help in finding it. The unusual assignment leads Korshak on a strange tour through Aurora's family of daughter worlds. In the process, he discovers that human nature changes little with time or place, and sinister interests are at work to undermine the mission's command structure and take over control, with a view to dominating the future culture that will arise following planetfall. The lost robot turns out to have "found religion" and believes that the voice of God is directing it on a sabotage operation that will advance the subversives' cause. Korshak's skills as an illusionist prove to be the crucial factor in foiling the plan.