Basil Rathbone is the batty physician of the title, a sophisticated gentleman who woos and weds several of his wealthy women patients. Unfortunately the ladies have a bad habit of dying prematurely, with the above-suspicion doctor diagnosing these deaths as the result of disease. Given the film's title, it isn't hard to figure out that the doctor has been knocking off his wives himself through sophisticated medical methods. An intriguing plot twist involves the doctor's loyal male assistant (Martin Kosleck), who tampers with the buried bodies of the victims to hide the evidence; though it's never made obvious by the script, it is implied that the doctor and his assistant have a strong sexual bond between them. The ex-fiance of Dr. Rathbone's latest bride (Ellen Drew) saves the woman from suffering the fate of her predecessors, leaving Rathbone no recourse but a suicidal plunge off a skyscraper.