In 19th-century Switzerland, Baron Victor Frankenstein (Peter Cushing) is in prison, awaiting execution for murder. He tells the story of his life to a visiting priest.
In 1860, Baron Victor Frankenstein, sentenced to death, escapes execution by the guillotine by having a priest beheaded and buried in his place, with the aid of one of his followers (the scuffle and substitution takes place offscreen, and is not realized until later). Three years later, Frankenstein, now going by the alias of Doctor Victor Stein, has become a successful physician in Carlsbruck, catering to the wealthy while also attending to the poor in a paupers' hospital. Hans Kleve, a junior member of the medical council, recognises him and blackmails him into allowing him to become his apprentice.
A man is taken from a cart and taunts the police and the priest escorting him to the guillotine, where he is to be executed for murder. The man spots his son, Hans, in a nearby copse and begs that he should not see him die. Despite the priest's attempts to shoo him away, Hans watches as his father is positioned under the blade. He yells, "Papa!" Then the blade falls, and Hans flees.
While illegally procuring a brain for his next experiment, Baron Victor Frankenstein is surprised by a thief when he returns to his lab. The Baron destroys most of the evidence and moves on, with a haughty police inspector on his trail. He obtains a room at a boarding house run by Anna, whose fiance Karl is a doctor at the local insane asylum where a former scientific collaborator of the Baron's, who has lost his mind, now resides.
Victor Frankenstein, a cold, arrogant and womanizing genius, is angry when his father forbids him to continue his anatomy experiments. He ruthlessly murders his father by sabotaging the old man's shotgun, consequently inheriting the title of Baron von Frankenstein and the family fortune. He uses the money to enter medical school in Vienna, but is forced to return home when he impregnates the daughter of the Dean (education).
Frankenstein (Cushing) is housed at an insane asylum where he has been made a surgeon, and has a number of privileges, as he holds secret information on Adolf Klauss, the asylum's corrupt and perverted director (John Stratton (actor)). The Baron, under the alias of Dr. Carl Victor, uses his position to continue his experiments in the creation of man.
