The Ringworld is a landmark engineering achievement, a flat band three million times the surface of the Earth, encircling a distant star. Home to trillions of inhabitants, not all of whom are human, and host to amazing technological wonders, the Ringworld is unique in all of the universe.

Explorer Louis Wu, an Earth-born human who was part of the first expedition to Ringworld, becomes enmeshed in interplanetary and interspecies intrigue as war, and a powerful new weapon, threaten to tear the Ringworld apart forever. Now the future of Ringworld lies in its children.