An obsessed scientist assembles a living being from parts of exhumed corpses.
Henry Frankenstein is a doctor who is trying to discover a way to make the dead walk. He succeeds and creates a monster that has to deal with living again.
Henry Frankenstein is a brilliant scientist who has been conducting experiments on the re-animation of lifeless bodies. He has conducted experiments on small animals and is now ready to create life in a man he has assembled from body parts he has been collecting from various sites such as graveyards or the gallows. His fiancée Elizabeth and friend Victor Moritz are worried about his health as he spends far too many hours in his laboratory on his experiments. He's successful and the creature he's made come to life is gentle but clearly afraid of fire. Henry's father, Baron Frankenstein, brings his son to his senses, and Henry agrees that the monster should be humanely destroyed. Before they can do so, however, the monster escapes, and in its innocence, it kills a little girl. The villagers rise up intent on destroying the murderous creature.
With the exception of his assistant Fritz, Dr. Henry Frankenstein has isolated himself from his family, friends and colleagues, including from his wealthy father Baron Frankenstein, his mentor Dr. Waldman, his best friend Victor Moritz, and his fiancée Elizabeth to who he was supposed to get married imminently. Unknown to them, what Dr. Frankenstein is doing with Fritz's assistance is work on a secret project. Using different parts from different dead people, he has stitched together a human, the most important component being the brain. Frankenstein's end goal is to show that he can make this stitched together being alive, in essence not reanimating a dead person, but rather making a live human as this creature was not human to begin with. Frankenstein is able to achieve his dream. Upon learning what Frankenstein has done, his friends, family and colleagues, especially Dr. Waldman, believe that he is treading in dangerous territory in creating what they believe is a monster, not only because of the nature of the project itself, but because the brain used, one stolen from Waldman's own laboratory, was "abnormal" in that it belonged to a criminal. What happens with the live creature may be a function of what he is taught, including how he is treated, than any evil inherent within him because of the brain. What happens may also affect Frankenstein and Elizabeth's marriage.
Dr. Frankenstein creates a monster from various posthumous 'donors' and combines them into a massive creature, to whom he wishes to bestow life. The movie centers on this monster and his struggle in this 'life after death'.
- Dr. Henry Frankenstein (Colin Clive) wants to build a man in his own image, using the body of a dead man. He and his assistant Fritz (Dwight Frye) dig up a freshly buried coffin and steal the body. When they realize the head and the brains of the body are severely damaged, they decide to steal a brain from Dr. Frankenstein's former teacher Dr. Waldman (Edward van Sloan). When Fritz accidentally drops the glass jar with the label "good brain" on it, on the floor, he decides to take the glass jar with the label "bad brain".
Using some kind of mysterious ray that Dr. Frankenstein discovered, the body is brought to life during a thunderstorm, and the monster of Frankenstein (Boris Karloff) is born.
Later, when Dr. Frankenstein realizes that he has created an aggressive monster, he and Fritz lock the monster up in a cell. When the monster is repeatedly bullied and provoked by Fritz, the monster eventually manages to kill him. When the monster escapes, he meets a little girl playing near the water. The monster and the girl throw flowers in the water. Enjoying the playing, the clumsy monster proceeds to pick up the girl and throw her in the water too. Later we learn that the little girl drowned in the incident, when her father carries her through the streets.
The city's population propel into an uproar, demanding the death of Frankenstein's monster. The monster is driven into an old mill, after which the people of the city set the mill on fire.