"We're returning to earth," Paul's father tells him. Paul is wildly excited, for all human beings on the planet Ganymede dream of going back to Earth some day. Then Paul finds out that he cannot take his robot Rex with him. Rex has been his constant companion for sixteen years. Leave him behind? Never! So begins a series of breathtaking adventures in space as Paul and his robot Rex attempt to outwit the forces that seek to separate them.
Author
Lester del Rey was an American science fiction author and editor. Del Rey is especially famous for his juvenile novels such as those which are part of the Winston Science Fiction series, and for Del Rey Books, the fantasy and science fiction branch of Ballantine Books edited by Lester del Rey and his fourth wife Judy-Lynn del Rey. Also published as: Philip St. John Eric van Lihn Erik van Lhin Kenneth Wright Edson McCann (with Frederik Pohl)
