Clytemnestra enters from the palace, revealing the corpses of Agamemnon and Cassandra. Standing over them, Clytemnestra delivers a triumphant speech in which she proclaims that she killed Agamemnon and Cassandra, and all her prior actions and words were calculated to bring about that end. As the chorus expresses horror, Clytemnestra justifies her actions, presenting Agamemnon’s murder as punishment for his sacrifice of their daughter 10 years before. Likewise, Clytemnestra argues that she was right to kill Cassandra, her husband’s “plaything” (1439) and “lover” (1446), along with him. In a sung interchange, the chorus laments the death of Agamemnon as a continuation of the cycle of violence that began with Agamemnon’s father, Atreus, while Clytemnestra exults in what she perceives as the justice of her actions.

Aegisthus enters with his bodyguards. He delivers a florid speech in which he expresses joy and thanks for the death of Agamemnon and explains his motivations and role in the murder. Years before, Agamemnon’s father drove Aegisthus’s father, Thyestes, out of Argos; he later viciously killed Thyestes’s sons and tricked him into eating them. This savage act marked the origin of the curse on Atreus’s house.