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.
Count Dracula
John Carradine
Dr. Franz Edelmann
Onslow Stevens
Lawrence Stewart Talbot
Lon Chaney Jr.
Miliza Morelle
Martha O'Driscoll
Nina
Jane Adams
Police Inspector Holtz
Lionel Atwill
The Frankenstein Monster
Glenn Strange
Siegfried
Ludwig Stössel
Steinmuhl
Skelton Knaggs
Brahms - Coroner (uncredited)
Joseph E. Bernard
Villager (uncredited)
Dick Dickinson
Villager (uncredited)
Harry Lamont
Villager (uncredited)
Robert Robinson
Villager (uncredited)
Anne G. Sterling
Gendarme (uncredited)
Fred Cordova
Gendarme (uncredited)
Carey Harrison
(uncredited)
Gregory Marshall
(uncredited)
Beatrice Gray