At a London auction, Princess Sonia bids against her husband, exiled Prince Victor, for a Corot landscape in which incriminating letters Sonia wrote are hidden, but it is bought by Michael Lanyard, suspected of being the mysterious, international thief "The Lone Wolf." After Lanyard gives Sonia the letters, she divorces Victor, marries Lanyard and dies after bearing their daughter Sonia. Years later, Sonia, who thinks she is the daughter of the Princess' maid, is found by Victor, now the leader ...