The true story of Juana de Castilla (Pilar Lopez de Ayala), daughter of Queen Isabella of Spain, who married (and fell passionately in love with) Archduke Fernando of Austria. When Juana's mother and older brothers die in 1504, Juana becomes queen, but her discovery of her husband's many lovers leads to erratic behavior. It's the perfect opportunity for her cheating husband to declare Juana insane and himself king.