A scientist working on cures for rare afflictions, such as a bone softening agent made from molds to allow him to correct the spinal deformity of his nurse, finds the physical causes of lycanthropy in wolf-man Larry Talbot and of vampirism in Count Dracula, but himself becomes afflicted with homicidal madness while exchanging blood with Dracula.

• Universal Pictures
• John Carradine
• Onslow Stevens
• Lon Chaney Jr.
• Martha O'Driscoll
• Jane Adams
• Lionel Atwill
• Glenn Strange
• Ludwig Stössel