Near the end of the 19th century, Prof. John Mayer and his assistant, the scientist Dr. Isabel Reed, accidentally invent a powerful ray. An alien travels to Earth to destroy the machine since it would be a threat to the universe. He initially possesses the mind of Thomas, a sex maniac and serial killer, to get close to Mayer during the demonstration of the machine to scientists and the military. Mayer's niece, Laura, meets an acquaintance of her uncle, the chemist Dr. Paul Rosten, and Mayer invites him to join the research. When Thomas gets close to Mayer, the alien also possesses his mind in order to destroy the device and his notes. Meanwhile, Thomas is not able to control his murderous impulses and attacks several women with a straight razor.
Boris Karloff
Enrique Guzmán
Christa Linder
Maura Monti
Yerye Beirute
Tere Valez
Griselda Mejía
Sergio Kleiner
Mariela Flores
Tito Novaro
Sergio Virel
Nathanael León
Carlos León
Rosángela Balbó
Julián de Meriche
Arturo Fernández