Ten thousand men and women, exiled by the restrictive governments of Earth, are riding a man-made habitat to the planet Saturn. They form a volatile community. Some are innocents like Holly Lane, or Manuel Gaeta. Others are idealists like Edouard Urbain, or Kris Cardenas and Nadia Wunderly. And some have much more dangerous plans. Malcolm Eberly, has been placed aboard the Saturn-bound habitat to take over its government. As the mammoth spacecraft nears its destination Eberly manoeuvres to take control of the habitat. His manipulations lead to murder and Holly becomes a hunted fugitive in the habitat's maze of tunnels and underground passageways. Meanwhile, frustrated by Dr. Urbain's intransigence, Gaeta prepares to fly solo through the rings, abetted by Wunderly and Cardenas. What he finds there challenges everyone living in the habitat.