England, 1888. The most famous detective of all time Sherlock Holmes (Christopher Plummer) and his assistant Dr. Watson (James Mason) are trying to stop Jack the Ripper who is killing prostitutes. But gradually it turns out that this maniac is just a cover for the real killer, who hunts not all the girls of easy behavior, but only those who are aware of the secret of Annie Crook (Genevieve Bugeaud). And Annie is the mother of a child with royal blood in her veins….