Three Weeks is the story of Englishman Paul Verdayne (Simon MacCorkindale), who is sent abroad by his aristocratic parents to break up an unsuitable love affair (he has fallen for a parson's daughter). In Lucerne, he meets a mysterious woman dressed all in black who exudes an hypnotic fascination. Paul and the Lady, who is a Balkan queen on the run from her degenerate and cruel husband, begin a passionate affair. She and Paul spend three weeks together where they make love on tiger skins amid masses of exotic flowers. When the three weeks are up and the Lady leaves Paul, he faints and is ill for a time. Months later, Paul receives a message from the Lady that his son has been born. Still later, Paul finds out that the Lady was killed by her degenerate husband who was himself killed by the Lady's servants. Paul's son is now the ruler and the Regent grants Paul permission to go to the ceremony and see his handsome young son proclaimed King.