The film begins with Baron Charles Frankenstein, his monster, Dr. Zalhus, and his assistant Paulus creating a female mate named Eva for the monster. Eva is physically identical to a human and lacking the deformities of the monster. As such, she is revolted by the monster and rejects him. This causes the monster to fly into a rage and destroy Frankenstein's laboratory. Frankenstein, believing himself and Eva to be the only survivors, flees with her back to Castle Frankenstein. There he falls in love with her and pursues the goal of making her a perfect human mate.
The monster, having survived, wanders into the countryside where he befriends a dwarf, Rinaldo. They become involved with a circus owner who eventually kills Rinaldo, causing the monster to sink into a state of deep sorrow and rage. He decides to return to Castle Frankenstein to retrieve his mate. At this time, Eva discovers that she shares a psychic link with the monster. She rejects the Baron as the monster is returning to the castle to rescue her. In the film's ending, the Baron falls to his death, and the monster and Eva reunite with each other and head off to Venice.