A scientist invents a formula that can actually keeps body parts alive while detached from the body. He keeps a dogs head alive and the serum is successful.
However when the scientist has a heart attack and dies his insane assistant cuts off his head, and using the serum keeps the doctor's head alive.
The insane one is played with glee by Horst Frank, and he really plays it for all it is worth. His main objective is to give an attractive hunchback nurse a new body and he needs the doctors help, so he keeps the head alive until he can complete the operation on the nurse, whom he wants for himself at all costs.
This movie is somewhat of a cross between a film noir and a horror film. The beautiful black and white photography does nothing but add to the film.
If you like bizarre horror films, I would really recommend this.