Anthropologist Dr. Brockton (Joan Crawford) believes she has discovered the missing link in this flat science fiction drama. The creature is found in a cave and brought to her laboratory to undergo tests for her research. The hairy beast with the face of a monkey loves classical music and hates rock & roll. When one of the slack-jawed yokels opens his cage, he escapes and goes on a killing rampage as he tries to return to his cave. In a gentle moment with a little girl, the beast shows a tender side that recalls a scene from Frankenstein. Soon troops are called in, despite Brockton's protest to entomb the creature by dynamiting the entrance to the cave. This was the last film for Joan Crawford, an inglorious way to end a legendary film career.