19th Century Switzerland. Baron Victor Frankenstein waits to be executed after being convicted of murder. Instead of confessing his sins to the attending priest, Frankenstein maintains his innocence, relating the events that led him to the guillotine.

Orphaned at an early age, Frankenstein inherits a fortune and his father's title. He engages Paul Krempe as a tutor. In a couple of years, Frankenstein has learned everything that he can, and the two men now work together researching the mysteries of life and death.

After years of research and experimentation, Frankenstein and Krempe succeed in bringing a dead puppy back to life. Krempe is ecstatic, seeing their discovery as a means to revolutionise surgical procedures. Frankenstein, however, sees this success as a prelude to creating the perfect human being out of the ideal constituent parts.

Despite misgivings, Krempe helps Frankenstein steal the body of a hanged highwayman. Frankenstein is unimpressed with the cadaver; the hands are clumsy, and the head has been attacked by crows. He chops off the offending parts, disposes of them in an acid bath, and prepares to replace them with more suitable specimens.

Ignoring Krempe's pleas for caution, Frankenstein sets off into the night. During his absence, his fiancée, Elizabeth, arrives to stay at his castle. Upon his return, Frankenstein greets her, then leads Krempe to the laboratory. He unwraps a pair of hands that once belonged to Bardello, a famous sculptor.

Krempe is horrified by the turn that their research has now taken, and urges Frankenstein to stop work. When he refuses, Krempe urges Elizabeth to leave the castle, but she will not leave her husband-to-be.

When Frankenstein returns from the Municipal Charnel House with a jar filled with eyes, Krempe refuses to help him any longer. Undaunted, Frankenstein sets about obtaining a fresh brain for his creation, inviting Professor Bernstein, the greatest scientific mind in Europe, to a dinner party. Frankenstein pushes Bernstein from a balcony, making it look like an accident.

Bernstein's body is interred in the Frankenstein family vault. After the funeral, Frankenstein opens the coffin and steals the brain. Krempe interrupts him; they fight and the brain is damaged in the ensuing scuffle.

Inserting the damaged brain into the body, Frankenstein attempts to animate the creature, but fails because he needs another person to help operate the machinery. As he seeks out Krempe's aid, a bolt of lightning strikes the castle and completes the animation process. The creature tries to kill Frankenstein, but Krempe knocks it unconscious.

The creature is chained up in the basement, too dangerous to be allowed its freedom. As Frankenstein blames Krempe for the failure of his experiment, the creature breaks its bonds and escapes into the nearby forest.

Frankenstein and Krempe follow the creature's trail, only to find that it has murdered an old blind man and his grandson. Despite Frankenstein's protestations, Krempe shoots the creature in the head, killing it instantly. They then proceed to bury the body in a woodland clearing.

Unbeknownst to Krempe, Frankenstein returns to the grave and digs up the creature. He brings it back to life, hoping to repair the brain damage that has turned it into a killer. When Frankenstein's housemaid tells him that she is pregnant and that she will tell Elizabeth of their affair, he lures her down to the basement and lets the creature kill her.

On the eve of their wedding, Frankenstein and Elizabeth hold a party at the castle. Krempe arrives late, and Frankenstein takes him down to the basement. He is enraged to see that the creature is alive, and is not placated by Frankenstein's reassurance that a lobotomy has cured its murderous impulses. Krempe sets off to inform the authorities.

As Frankenstein pursues Krempe, the creature breaks its bonds again and stalks Elizabeth around the castle. Frankenstein and Krempe spot the creature staggering along the battlements.

Frankenstein shoots at the creature, but wounds Elizabeth instead. He sets fire to the creature, which then plunges through a skylight into the acid bath and dissolves.

Back in the jail cell, the priest won't believe Frankenstein's story. Krempe, accompanied by Elizabeth, also refuses to confirm what happened. Frankenstein is led away to the guillotine.