In 1880, Sir Robert Cargrave, a London physician known for his experimental work in paralysis treatment, is summoned to Gorslava by the mysterious Baron Sardonicus—who is now married to Cargrave's former wife, Maude—to treat his disfigurement. When Cargrave arrives, he finds the masked baron is a cruel sadist who has threatened to harm Maude if he is not successfully cured.