Bronson Alpha, the larger of two rogue planets, collided with and destroyed the Earth, before leaving the solar system. However, its companion, the roughly Earth-sized Bronson Beta remained behind and settled into a stable, but eccentric, orbit around the sun.
In a desperate attempt to save a portion of humanity, the
United States and several other countries feverishly constructed space arks to transport a select few to Bronson Beta. The Americans, under the leadership of Cole Hendron, managed to launch two space Arks, carrying hundreds of people, as well as the animals, plants and knowledge they will need to hopefully survive on the alien planet. Both American ships reach this new world, as do at least two others, though all four become separated and each is unaware of the fates of the others.
The survivors of Hendron's own smaller Ark set out to establish a colony, aware (from a road they find) that an alien civilization once existed on Bronson Beta. Tony Drake and another associate scout out for suitable farmland, but during their return journey following the alien road, the two men come across a vehicle. After a mysterious disease strikes the camp, killing three colonists, Hendron forbids exploration, but some of the colonists defy him and strike out, bringing back wood from a distant forest. That night, an aircraft passes near the camp, beating a hasty retreat when the campfire is spotted.
Kyto, Tony's Japanese former manservant, finds a piece of paper blowing in the wind; it reveals that a group made up of
Germans,
Russians and
Japanese intend to establish a "
soviet" called "The Dominion of Asian Realists."
At Hendron's order, an exploratory aircraft is built from remnants of the Ark and its rockets, and Tony Drake sets off with writer Eliot James. They follow the road and discover a domed city. The Bronson Beta natives were essentially humanoid and had considerably higher technology than humanity. This species built five such cities to survive their world's departure into interstellar space, but ultimately decided to simply become extinct after they were completed.
The Americans explore the city. Then they fly south and discover a searchlight in the dark. It comes from the second American Ark, which had a disastrous landing. There is a joyous reunion with its commander, Dave Ransdell. Ransdell's camp also encountered a mysterious aircraft.
Tony and Ransdell fly back to Hendron's camp, finding that Hendron is visibly deteriorating in health and mind. Tony is jealous that Ransdell apparently will become their new leader and will also have Eve, Hendron's daughter, as his wife. Eve, acting as Hendron's regent, sends Tony to deliver a radio to the Ransdell camp. The first message reports that Hendron's camp has come under some sort of attack. Tony and one of Ransdell's men investigate; they find everyone lying on the ground.
They discover everyone is alive, but drugged; they give the doctor antidotes and then hear an aircraft approaching, occupied by men with Slavic features. After the aircraft leaves, Tony prepares weapons (rocket tubes from the Ark) to defend the camp. An armada arrives soon afterward, but is totally obliterated.
The people gradually wake up. Hendron hands command over to Tony, to Ransdell's relief. Tony decides to occupy one of the alien cities, not the one they found, but another one nearby; they follow the road there.
During the trip, they encounter an alien automobile driven by a British woman; she explains that a British ship also made it from Earth, but landed in a lake; they were found the next day by the "Dominion of Asian Realists" group, which Hendron nicknames "
Midianites", and enslaved. The Midianites' society is structured like an ant farm, the colony being all important and the people nothing, but the top rulers live luxuriously.
Tony's group settle into the alien city, and tractors are sent to bring Ransdell's contingent. Tony names their new home Hendron. Hendron himself died just as the convoy came into view of the city. The scientists manage, with the Briton's help, to figure out how to charge the batteries and operate the machinery. They also find hangars housing enemy aircraft; some are armed and used for air defense.
Meanwhile, the planet is approaching
aphelion, and nobody is entirely certain that it is in a stable orbit around the sun. The weather gets colder, and one night, the Midianites disconnect the city's power supply. One woman defects to the Midianites, while four others attempt to reach the Midianite city using a high-speed car in an underground service tunnel. They are unsuccessful, but the female "defector" kills the Midianite leader, defeats his key people, and allows the British to take control.
The Dominion is defeated, and the victorious American/British coalition settles into the domed cities, along with the former Midianites. While challenges remain, their immediate needs for shelter, energy, and food are taken care of. The story ends on an optimistic note with a reference to the first pregnancy among the colonists, Eve and Tony's, and the confirmation that they have passed aphelion and are definitely locked into orbit around the sun.
The book ends with an obvious setup for yet another sequel,[
citation needed] but it was never written, and, as far as is known, it was never plotted out.
