I have not figured out what the chosen title has to do with the movie. This is another gathering of monsters just like the HOUSE OF FRANKENSTEIN. Not exactly a masterful plot, but Universal needed to capitalize again.
Dr. Edelman (Onslow Stevens) is either very ambitious or over the top in the ego department. He is working on the cure to keep Larry Talbot from turning into the Wolf Man. Somehow Count Dracula happens to drop by to get a fix on his vampirism. And rounding out the good doctor's experiments is the restoring of the Frankenstein monster's energy. Along the way, the kind hearted doctor's blood is tainted with that of Dracula.
John Carradine plays Dracula again. This time he is more convincing. Lon Chaney Jr. as usual is the soulful Wolf Man. Glenn Strange is the Frankenstein monster, who has very little to do this outing. Also with mentionable roles are Lionel Atwill and Martha O'Driscoll.