Easter 1903. In the slums of London, French prostitutes are found crucified. Mysterious messages are discovered in the clothing of the victims. These crucifixion murders cause an international sensation and jeopardize an upcoming state visit by the English king to the French president, during which the two superpowers hope to forge closer ties.

Inspector Bradstreet of Scotland Yard and the London police are baffled. To solve the series of murders, Sherlock Holmes is directly commissioned by the king. After deciphering the coded messages, a breathtaking cat-and-mouse game with the perpetrators begins, one that even temporarily drives a wedge between Dr. Watson and his friend.