Three men are launched from Cape Kennedy in a typical Apollo style launch; a "Red Chinese" agent is killed in the water nearby before he can sabotage the rocket launch. The President of the United States announces that the three men and their ship will be the nucleus of a new nation, and asks Americans to turn their lights on that night to show support for the project. The astronauts take photos of the Earth's surface as they orbit, to be processed later to determine the level of public support for the idea. The results indicate widespread support for a new nation in outer space. The movie skips ahead several years to show a shuttle approaching a space station, a huge, rotating city known as Earth II, with technology at its disposal that makes it fairly easy to maneuver around the city and supply it and the thousands — from many nations — now living aboard. There is a family aboard the shuttle — Frank, Lisa and Matt Karger — who are new immigrants to the colony of many national origins. Shortly after arrival, Earth II's administrators, including David Seville, become aware of a nuclear warhead in orbit that comes close to Earth II every few hours. The warhead was launched by the People's Republic of China. Earth II requests a meeting with PRC representatives through the UN ; at the meeting, the PRC refuses to remove the weapon and threatens to detonate it if it is tampered with. Earth II has a direct democracy process known as a "D&D" — Discussion and Decision. The newly arrived Frank Karger initiates a D&D to decide on dealing with the warhead directly. After some of the citizens, including Russian emigre Ilyana Kovalefskii make their statements, the vote is to act. Two men, including Ilyana's husband Anton go out in a tug to deactivate the warhead, but Anton is electrocuted when the Chinese activate the weapon. The weapon does not explode, because Kovalefskii had already cut several wires in the arming device. The tug operator rescues the technician, discards his tool caddies, secures the bomb and brings both back to Earth II. Ilyana is told that Anton will be disabled for life as a result of his injuries unless surgery is attempted. Ilyana approves the surgery. Meanwhile, Lisa Karger doesn't want the bomb aboard, and is alarmed at Frank's intent to initiate a D&D on Earth II becoming a nuclear power. When someone tells her one way to dispose of the bomb is to fire it at the Sun, she blows the hatch cover on the holding bay, waits for the Sun to come into the view, and launches the bomb at it. The Earth's gravitational pull is greater however, and the bomb falls toward the Earth and will detonate over the Great Lakes region. Ilyana has observed the operation on her husband — in an operating room with medical personnel standing on both the floor and ceiling — but after it is completed, Anton abruptly dies. The tug operator retrieves the warhead, but not before the warhead's casing disintegrates in the Earth's atmosphere. The bomb is brought back and put into the same holding bay, and station rotation is slowed as much as possible while a crew works to permanently deactivate the bomb. The city is still rotating enough to bring the Sun into view through the opening and the temperature is rising, threatening to melt safeties and detonate the bomb. A pilot takes a tug out and puts its nose against one of the main struts of the city, then fires its engines to stop rotation altogether. The sun's light is partly shining into the holding bay, the temperature at a crucial level. The technicians find melted metal that makes it necessary to drill in order to remove some components. The disarming is completed, the rotation of the city is restarted, Karger reverses his decision regarding a D&D on Earth II's nuclear weapons status, and the bomb is launched toward the Sun for disposal.
