Doctor Gustav Niemann (Boris Karloff) escapes from prison with his hunchback assistant Daniel (J. Carrol Naish), who hopes his master will create a beautiful new body for him. They murder a showman named Professor Campini and take over his travelling horror exhibit. Seeking revenge on Burgomaster Hussmann (Sig Ruman), who was responsible for putting him in prison, Niemann revives Count Dracula (John Carradine), who seduces Hussmann’s granddaughter Rita (Ann Gwynne) and kills Hussmann. Then Niemann destroys Dracula’s coffin, causing him to die in the sunlight.
Niemann and Daniel journey to the ruins of Castle Frankenstein in Visaria, where they discover the bodies of Frankenstein’s monster (Glenn Strange) and Larry Talbot (Lon Chaney Jr.), the Wolf Man, frozen in the ice. Niemann thaws them out and promises Talbot a cure for his lycanthropy, but he really wants to use the monster to exact revenge on his enemies. Talbot becomes the Wolf Man and kills a man, sending the villagers into a frenzy.
Niemann and Daniel save a Gypsy girl named Ilonka (Elena Verdugo) and Daniel falls for her, though she falls for Talbot. She does not care that he is a werewolf. She just wants to help the big sad-eyed lug. The monster awakes and Talbot turns at the same time. The werewolf fatally wounds Ilonka, but she shoots him with a silver bullet. Daniel turns on Niemann, but the monster throws Daniel out the window and carries Niemann outside. The villagers chase them into quicksand and they die.
The film was directed by Erle C. Kenton, based on a story called The Devil’s Brood, by Curt Siodmak. It was produced by Paul Malvern for Universal. The mummy Kharis was also supposed to be in it, but that did not happen. John Carradine entertained the cast and crew with Shakespearean recitation and Lon Chaney would prepare luncheons. Glenn Strange was injured by being placed in a glass case without air, He accidentally threw J. Carrol Naish out a window onto concrete, missing a mattress, but he was saved by his hunchback costume. The music was not canned like that of most of the Universal monster films, but had a score written by Hans Salter, Paul Dessau, and Charles Previn, André Previn’s cousin.
Film critics were unkind, calling it more ludicrous than terrifying, though the music was praised and the cast was considered impressive. Elena Verdugo’s scream was so good it was not dubbed. Boris Karloff gave Glenn Strange pointers on how to play Frankenstein’s monster. A sequence in which Dracula’s shadow transformed into a vampire bat was created by Universal’s animator Walter Lantz, most well-known for Woody Woodpecker. The love of the hunchback for the Gypsy dancer was stolen from Notre Dame de Paris, by Victor Hugo. Hans Salter’s music score is so powerful it drowns out the Wolf Man’s howl. The land where Universal Studios now sits was owned by Elena Verdugo’s Spanish ancestors. She is best known, perhaps, as the receptionist for Marcus Welby, MD.