Colonel Pete Moore (Glenn Ford) is commander of the Whitney Radar Test Group, which has been experiencing electrical difficulties aboard its aircraft. To ferret out the problem, he sends a four-man crew on Flight 412. Shortly into the test, the jet picks up three blips on radar, and subsequently, two fighters scramble and mysteriously disappear. At this point, Flight 412 is monitored and forced to land by Digger Control, a top-level, military intelligence group that debunks UFO information. The intrepid colonel, kept in the dark about his crew, decides to investigate the matter himself.

Englishman Robinson Crusoe, stranded alone on an island for years, is overjoyed to find a fellow man, a black islander whom he names Friday. But Crusoe cannot overcome the shackles of his own heritage and upbringing and is incapable of seeing Friday as anything other than a savage who needs Crusoe's brand of cultural and religious enlightenment. Friday attempts to share his own more generous and unashamed culture, but ultimately realizes that Crusoe can never see him as anything but an inferior being. With that awareness, Friday sets out to turn the tables on Crusoe.