A botanist has spent three years aboard the space freighter "Valley Forge" preserving the only botanical specimens left from Earth under huge geodesic domes. When he receives orders to destroy the project and return home, he rebels and hijacks the space craft, killing his fellow crewman and injuring himself. He plunges the ship into the gaseous Rings of Saturn, where he embarks on the loneliest adventure of all with only two drone robots to keep him company.