The Earth is crowded and food is rationed, but a colony on Ganymede, one of the moons of Jupiter, offers an escape for teenager Bill Lermer and his family. Back on Earth, the move sounded like a grand adventure, but Bill soon realizes that life on the frontier is dangerous, and in an alien world with no safety nets, nature is cruelly unforgiving of even small mistakes. Bill's new home is a world of unearthly wonders -- and heartbreaking tragedy. He will face hardships, survive dangers, and grow up fast, meeting the challenge of opening up a new world for humanity and finding strengths within himself that he had never suspected existed.