Dr. Frankenstein (Colin Clive), a young man obsessed with bringing the dead to life, and his loyal hunchbacked assistant Fritz (Dwight Frye) troll the graveyards for corpses. They have assembled a composite corpse which is brought to life during an electrical storm. Unfortunately, the former corpse (Boris Karloff) is a violent monster with a criminal's brain. This being a film, the monster escapes to terrorize the rural German countryside, spoiling the wedding of Dr. Frankenstein to blonde mother substitute Mae Clarke.

There is much to enjoy about "Frankenstein". The sets, especially the laboratory, the mill, and the German village, are excellent. The performances of Clive, Frye and Karloff are so memorable that they defined the stereotypes (respectively) of the mad scientist, his hunchbacked assistant (more often named 'Igor'), and Frankenstein's monster. Ironically, Karloff in later years would be acknowledged for his perfect-diction speaking voice (e.g. "The Grinch who Stole Christmas") but here his character, in the role that made him famous, only gets to grunt.

Although it was only James Whales' third film as a director, he has the touch of a master. The close-ups of Clive and (especially) Karloff are effective, and the scene with the peasant (Michael Mark) carrying his lifeless daughter (Marilyn Harris) through the astonished village may be the best in the film. Comic relief is provided by Frederick Kerr as Dr. Frankenstein's curmudgeony father.

Universal Studios felt the need to soften the impact of this early horror film. Edward Van Sloan, who has a small role as Frankenstein's precise university professor, begins "Frankenstein" with an introduction warning the faint of heart to exit the theatre. To Whale's distress, the scene with Karloff tossing Harris into the lake was cut (although it has since been restored). The ending was also modified, with Dr. Frankenstein surviving to see a happy ending with Clarke.