Jon Bradburn, a former air traffic controller at Englands Manchester Airport, is picked up by aliens from the planet Zel. After interrogation, he is persuaded to become a "teacher of men."

Its become obvious to the Zellians that humankind is nearing the point where self-destruction is imminent, consuming Earth in atomic warfare.

Jon is the last in a long line of "teachers" provided by the Zellians, being "prepared and modified" mentally and physically for the role he will have to play. He is endowed with superhuman strength and intelligence, as well as the promise of longevity beyond that...