When Tom Corbett and his Polaris unit mates, Roger and Astro, were assigned to the great expedition of one thousand space ships carrying pioneer colonists billions of miles to the satellite Roald, they did not dream that they were facing the most thrilling adventures of their careers.

       Leadership of the expedition fell into the ruthless hands of one Paul Vidac who, learning that there was uranium on the satellite whither they were bound, decided to take over the new colony for himself. At every step of his evil design he found himself dealing with the three cadets who came to the aid of the pioneers.

       When the long journey was over and it was time to make a landing on the distant Star satellite, a mysterious and powerful force (the presence of the uranium) so affected the instruments that almost half of the great fleet of space ships crashed into each other or onto the landing field. Thanks to Tom's coolness and quick thinking, the Polaris made a safe landing. Once landed on Roald the adventures came thick and fast, and the evil designs of the cold-blooded Vidac and his greedy henchmen were frustrated by the three cadets and their old commander, Captain Strong.