Dr. Victor Frankenstein works in the catacombs of Candlewood Castle on a serum that he hopes will give him eternal life and superhuman strength. In order to lure Dracula into his clutches, he has his daughter Elisabeth kidnapped from the vampire lord's castle by the creature he created, Boris. But in addition to the blood of Dracula, he also needs the heart of a mummy, a piece of skin of the invisible and the self-regenerating powers of the werewolf. Only if all monsters join forces will they be able to thwart Frankenstein's insane plans.