Greg Zhor is a member of the copper-skinned Rihns, a peaceful people descended from the aboriginal Martians and the first terrestrials from Earth to settle on Mars. Zhor rose to prominence due to his research in atomic energy. The Rhins lived in harmony with the pure-blooded humans until a mechanic named Karragon realized his ability to manipulate the people through his oratory skills. Karragon became dictator of Mars. His followers were called Thelists. He encouraged the Terrestrials to hatred against the Rhins. Greg Zhor is degraded to a test tube cleaner by bigoted Thelist scientists.