An hour before his execution, Baron Victor Frankenstein calls for a priest. Refusing spiritual comfort, he begs the priest to listen to his story: As a wealthy, young orphan, dissatisfied with the local schoolteacher and eager for knowledge, Victor advertises for a tutor and hires Paul Krempe, who becomes his mentor and later his partner in scientific inquiry. In the laboratory above Victor’s mansion, they discover the key to life and are able to revive a dead puppy. Although Paul wants to share their discovery with fellow scientists, Victor wants to continue their work using humans. After bringing the dead back to life, he now wants to create life and convinces the reluctant Paul to help him retrieve the corpse of a recently hanged man to use as the basis for a new human. When Victor gathers high-quality body parts from the charnel house, Paul becomes increasingly uneasy, finally reaching the point of refusing to assist. While Victor travels to another city to obtain the hands of a recently-deceased, famous sculptor, his cousin Elizabeth arrives, after the death of her mother. Having loved Victor since childhood, she is eager to marry him, in fulfillment of an arrangement their mothers made. Although Paul hopes that her presence will persuade Victor to discontinue his grisly experiments, Victor, who is having an affair with the maid, Justine, behaves courteously, but remains unchanged. After mentioning that he needs the brains of a genius for his creation, Victor invites the elderly Professor Bernstein for an extended visit. The professor is grateful for the hospitality and for what he thinks is Victor's interest in his work. In a conversation with Paul, Elizabeth and Victor, the professor suggests that having knowledge is different from knowing what to do with it and explains convincingly the scientist’s dilemma of handing over discoveries to people who mishandle the information. At the end of the evening, while leading the professor to his bedchamber, Victor maneuvers him into falling over the balcony’s banister to his death. Appearing to act out of generosity, Victor buries Bernstein, who has no living relatives, in his family vault, but later robs his grave. Knowing that Victor is using the professor’s brain for his experiment, Paul accuses him of murder and mutilation. When their resulting fight results in the lab being damaged, Victor orders Paul to leave. Before going, Paul enters Elizabeth’s bedchamber to beg her to leave with him, claiming he has stayed only to protect her. He tells her that Victor, although neither wicked nor insane, is so wrapped up in his experiments that he cannot see the consequences and warns her that she is in physical and mental danger. However, Elizabeth is in love with Victor and wishes to help with his work, even though she knows nothing about it. Later, when Victor is ready to use an electrical charge to bring his monster to life, he asks for Paul’s help. Paul at first refuses, until Victor threatens to train Elizabeth for the job. Fearing that Elizabeth would be traumatized to learn the truth about Victor's work, Paul unhappily agrees to help. Victor and Paul then harness electricity during a storm to bring the creature to life. Its first act is to try to strangle Victor, but Paul stops him and the creature is then strapped down. To no avail, Paul urges Victor to destroy the monster, but Victor refuses. The creature then escapes and kills an old blind man who is hiking in the mountains with his young grandson. Without alerting the police, Paul and Victor track down the monster, and Paul shoots it in the head, against Victor’s wishes. They bury the creature, but Victor later unearths it and resumes his experiments, soon returning it to life. Upon learning of Victor’s plans to marry Elizabeth, Justine tells him that she is pregnant. When he refuses to marry her, she threatens to inform the authorities about his sinister work. During the night, she sneaks into the laboratory, and after Victor locks her inside, she is killed by the creature. On their wedding night, Victor leaves Elizabeth to work in his laboratory. Paul, who missed the wedding ceremony, arrives that night and learns that the monster, which is now a brain-damaged, cowering creature, has been revived. Blaming Paul’s bullet for the change in the creature’s demeanor, Victor says he plans to find a new brain for him. Paul leaves to alert the authorities, and Victor follows, hoping to dissuade him. From the mansion's ground they see that the creature has broken his chains and wandered out onto a roof carrying Elizabeth, whom he captured after her curiosity led her into the laboratory. Victor shoots at the monster, but wounds Elizabeth instead, and the monster moves toward him. In the ensuing struggle, Victor attacks him with a lantern, causing the monster to catch fire and fall through the roof skylight into an acid bath. In his jail cell, Victor tells the disbelieving priest that his “life’s work” was destroyed. Paul, the only person who can confirm Victor’s story, arrives, but refuses to corrorborate his account. The priest, warden and Paul then leave Victor's cell. Outside, Paul, who has always cared for Elizabeth, tells her that “there is nothing we can do for him now” and takes her home. Later, Victor, who is sentenced to die for the murder of Justine, Bernstein and the old man, is taken to the guillotine.