Tyna Starr is a lab assistant working for Professor Hal Garth. Professor Garth is developing robots, which he thinks usurp the position of dogs to become "man's best friend". Tyna is a thrill-seeker, quitting her position with Garth to pursue adventure on Ganymede, a moon of Saturn. She seeks a manly man, not a boring thinker like Hal. Landing on Ganymede, she soon meets Rober Mannling, who soon fulfills her expectations of a space hero of the type she is seeking. His first task is to defeat a group of Ganymede Thugs in protection of Tyna. He handily defeats the attackers, and impresses Tyna.