Condemned to be stoned to death for heresy (daring to question the Elders), Devon escapes Cypress Corners with his love Rachel. Her betrothed, Garth, follows to bring her back. They find they're on the Earthship Ark, headed for destruction.
Escaping from the savage descendants of the security crew, the three waken a technician from cryosleep to help them repair the ship and prevent the coming collision. But he is dying, and the wrong sort of specialist.
Searching for a way to repair the Ark, Devon, Rachel and Garth arrive at the Omicron biosphere, which may have some ancient technical books. All the women died long ago, and Rachel is mistaken for the goddess the men worship.
Ark craft Pisces has been searching for habitable planets for ten years - their time. On the Ark 409 years have passed, proving Einstein correct. But there are penalties to suffer for travelling that fast.
The trio discover an empty 'leisure' biosphere. Behind the scenes a ruthless scientist works to produce humans strong and savage enough to survive anything they may find on their new home - at the expense of friendship and trust.
The angry, embittered Dr Richards tries to escape the Ark with his daughter after triggering the ship's self-destruct mechanism. His capsule fails to launch, and the self-destruct can't be overridden. But there is a very dangerous fix.
A mysterious, bewitching art gallery proves to be the creation of Magnus, said to be the greatest mind in the universe. But who - or what - is he, and how can he help correct the course deviation that threatens the Ark with destruction?
The trio blunder into a sealed, highly industrialised biosphere, where outcasts die in the toxic air outside a sealed city ruled by a paranoid, self-deceiving leader who is preparing for war - if he could find a way out.
A year ago Oro of planet Exar crashed into the Ark, and with the help of Idona has been cannibalising Ark components to make repairs to his scoutship. Oro plans to take Idona back home with him - but then she meets, and falls for, Garth.
With Devon seriously injured, Rachel's call for help reaches the Astro-medic ship. At the same time an alien spacecraft is also appealing for assistance. The two main doctors - father and son - are at loggerheads: who do they try to save?
Unknown to the monarch, her power-hungry servant plots to rule the biosphere where the elite are forced to have implants that inflict pain, while the poor starve. Can the elite find their courage when he takes Rachel and Garth hostage?
Oro returns, offering to repair the Ark's faulty systems and fly them all to settle on Exar, which he claims is much like earth. Devon discovers he's lying, but can only prove it in a debate in which the loser will be killed.
The Ark's chief astronomer altered its course so he could study a comet: now the debris is seriously damaging the Ark. The thrusters that can move it to safety need to be fixed manually, and Devon volunteers for EVA to do the work.
A dome containing only a tropical garden, a lab, and millions of bees to pollinate the plants on humanity's new homeworld sounds perfect - but not when the leading scientist is breeding mutant bees with the ability to take over human minds.
Garth leaves his friends and heads back home, only to find himself recruited into the Ark's police, who are working with the police of an alien system to avert an interplanetary war. But their efforts are being thwarted from within.