In a gloomy London suburb a modern Jack the Ripper stalks at night, killing at random with brutal knife thrusts from behind. Three women fall victim to the murderer and the terrorized residents of Albert Park wait to see who will be next. Was it a madman who killed all three women, or were the murders part of a brilliantly contrived master plan?

Into this scene of confusion and fear comes Carolus Deene, the wealthy Gentleman Detective who teaches at a boys' public school; his avocation is solving crimes. Although the police resent his presence, the residents graduallv open up to this intelligent, sensitive man as he probes the motives behind the killings and solves the heinous crimes.