Based loosely on the classic gothic novel of 1817 by Mary Shelley, this story of scientific experimentation gone awry helped to inspire a modern genre.
The film is introduced with a "friendly warning" that it may horrify you. After a funeral young Henry Frankenstein (Colin Clive) and his humpbacked assistant Fritz (Dwight Frye) dig up the corpse and cut down a hanged man but still need a brain. Doctor Waldman (Edward Van Sloan) teaches his class the difference between a normal brain and that of a criminal. Later Fritz drops the normal brain and steals the criminal one. Frankenstein left the university so that he could continue his advanced experiments that attempt to re-create human life. His fiancée Elizabeth (Mae Clarke) asks for the help of her friend Victor Moritz and of Dr. Waldman. Victor calls Frankenstein crazy, but the young experimenter aims to show him he is wrong. He uses electricity and a powerful storm to stimulate life in a body he has put together from various corpses, and the hand moves. Dr. Waldman warns him of the danger and suggests he guard the creature. Fritz frightens the monster with a torch, and they have to chain it. After Fritz torments it, the monster breaks free. The doctor and Frankenstein decide to use an injection to kill it. When Elizabeth arrives with Henry's father Baron Frankenstein, Henry collapses. Doctor Waldman gives more injections, but the monster has built up a resistance. When the doctor begins to dissect it, the monster strangles him.
The celebration of Elizabeth and Henry's wedding is beginning. In the country a lonely girl wants to play with the monster, but it throws her into the lake. Elizabeth is afraid that something bad is going to happen, and news arrives that the doctor has been murdered. The monster enters the room of the bride Elizabeth. The father of the drowned girl arouses the town, and the burgomaster, alerted by Frankenstein of the fiend, organizes three search parties. Henry finds the monster in the hills; after a struggle, the monster carries Frankenstein up the mill tower and throws him down. The crowd sets fire to the mill, destroying it and the monster. Henry survives the fall and in the final scene is recovering at his father's house. The dramatic conclusion in the movie resolves the story quite differently than the novel in which the monster survives looking for friendship.
The power and popularity of this story seems to come from deep archetypal forces in the human psyche. The human attempt to take over the divine mystery of God and the soul in determining life and death leads to a horrifying aberration of human life. The mistreatment of the creature by Fritz does not help. The juxtaposition of an innocent bride with a crude monster stimulated sequels.