The sentient space traveling vessel Ship travels throughout the galaxy planting the human seed on various worlds. Ship always leaves with the promise of returning one day to judge humanity.

On one of these planets called Home, in which Ship left behind humanity (see Earthseed), the species divided into two branches (see Farseed). Inside of the dome left behind by Ship resides the Dome Dwellers who believe they are the pure humans abiding to the strict dictates of their creator by protecting "true humanity" while waiting for the second coming; they are high tech. Some people left the dome to live off the land near the great river as farmers and hunters; they are low tech. These River People believe they are adhering to the dream of Ship for mankind to expand and live in harmony on Home. Each side knows with total certainty the other side is contaminated. Ironically, though their visions are radically different, the two branches of humanity barter food for technological repairs.

Elderly Nuy of the River people sees strange light in the sky. She and her tribe assume Ship has returned for Judgment Day. Inside the dome, excitement and fear are high that Ship has come back as promised to see how humanity has fared. However, the radio experts find their communication devices fail to make contact with Ship and the Librarian remains silent as to how to proceed while the youngsters openly revolt. The River Dwellers are concerned that the Dome Dwellers have failed to provide them information as promised by their agreement; they wonder if the other side has sold them out so Nuy's great-granddaughters Bian and Arnagh begin a journey to the dome to learn what is going on.

With religious implications inside a Cold War bunker mentality as well as a profound comparison between a simple agrarian culture and a materialist life, Pamela Sargent provides a deep science fiction thriller. The author's underlying message is materialism without spiritual and nurturing purpose is futile.

The reactions to the perceived return of Ship is fascinating as the Dome Dwellers who insist they are "true" fear Judgment day; while the River People fear the Dome Dwellers have set them up to be condemned. Life for both groups will never be the same as the creator has returned to pronounce judgment on what humanity has become.

Although the two teens somewhat stand out from the masses, for most the River People are interchangeable except for Bian and Arnagh, and to a lesser degree Nuy. None of the Dome Dwellers feels fully developed beyond their specialization until late into the alleged return of the seed Seeker. On the other hand, Ship seems omnipotent with only Nuy willing to truly challenger the original planter.

Somewhat over simplified in terms of the value of technology, readers will appreciate the engaging science fiction thriller with its deep religious overtones; as the two branches of humanity face Judgment Day differently as revelations surface to what Ship hoped for them when he planted the seed of free will.