August 1572 France is torn apart in bitter religious wars. Marguerite, known as Margot, is proud and beautiful; the Catholic sister of King Charles IX, she is forced to marry the Protestant Henri de Navarre in an effort to reconcile her native France.

Six days after the wedding, the infamous St Bartholomew's Day massacre takes place, encouraged by Margots mother, the ruthless and scheming Catherine de Medici. Thousands of Protestants are brutally murdered, but one of them, La Mole who is badly wounded, knocks on Margots door in desperation. She takes him in and, for the first time in her life, she falls in love... with the enemy.