A mad scientist (played by J. Carrol Naish) descended from the original Dr. Frankenstein takes to murdering young women for experimentation in hopes of reviving his ancestor's creation, with help from his mute assistant (played by Lon Chaney, Jr.). Things start to heat up when Dracula (played by Zandor Vorkov) arrives and promises to revive Frankenstein's monster in return for a serum which will grant him immortality.