Baron Frankenstein (Peter Cushing) travels to a new town to meet Dr. Brandt with whom his has been corresponding and with whom he had hoped to collaborate. He arrives however to learn that Brandt is in a mental institution, having lost his mind completely. He takes a room in a boarding house run by the pretty young Anna who just happens to be engaged to Karl, a doctor who works at the asylum where Dr. Brandt is being kept. When Frankenstein learns that Karl has been stealing drugs, he blackmails him and Anna to work as his assistants. He is desperate to learn a secret that Brandt was going to share with him and kidnaps him with the intent of extracting that secret by transplanting his brain into another body. Also stars Veronica Carlson, Freddie Jones, Simon Ward and Thorley Walters.