The Greek fleet bound for Troy is becalmed. For the sake of a wind, Agamemnon, leader of the Greek forces, is persuaded that he must sacrifice his daughter Iphigenia. But as the priest raises his knife to slit the child's throat, the goddess Diana spirits her away. Clytemnestra, Agamemnon's wife, believing her beloved daughter to be dead, slays her husband in revenge on his return from the Trojan wars. Their son, Orestes, avenges his father's death by killing his mother. Now, years later, as Iphigenia, a prisoner of the temple of Diana, looks across the sea to Greece, longing to return home, her brother Orestes arrives...