Filmed under the title Prehistoric World, Teenage Caveman stars future Man From UNCLE Robert Vaughn as the eponymous hero, known only as The Boy. A member of a primitive tribe living in a desolate valley, The Boy has been warned never to journey into the Forbidden Area, lest disaster or death befall him. But after participating in a bear hunt, The Boy and his spear-carrying fellow tribesmen head into the Forbidden Area in search of fresh game. One by one, the intrepid hunters are killed off by quicksand, stock-footage dinosaurs and other such impediments to progress. Exiled by his tribe for venturing into the Forbidden Area, The Boy is compelled to live for a time in an isolated cave, where he is comforted by the Maiden (Darrah Marshall), who has fallen in love with him. Later on, the Boy once more risks life and limb by entering the Forbidden Area. It is at this point that he is told the horrible truth of the Valley's history by a very old man who is dressed in what looks like a 20th-century radiation suit. Without revealing the "surprise" denoument (surprising only to those who've never seen a post-apocalyptic movie), it can be noted that Teenage Cavemen comes to a close with the words "The Beginning."