On a frozen planet, the Alphans encounter shipwrecked humans from a lost expedition. The expatriates from Earth enjoy an idyllic existence: they have been made immortal and have lived there for over 880 years. They invite the Alphans to join them in paradise, but dissidents reveal all is not at it seems, teaching Koenig that immortality comes with a price.

The Alphans are visited by a bizarre spacecraft, whose request for supplies hides a deeper purpose. The ship, Gwent, is found to be sentient, the attempt of a vain alien genius to live forever. Powerful, unstable and craving companionship, Gwent intends for Koenig, Helena and Bergman to replace its aged, dying creator.