Aigisthos enters the stage, saying that he comes at the summons of a messenger. He has heard the news of Orestes's death, and calls it far from welcome. The house is still festering from the wounds of the last bloody murder, and this new burden might bring the place down. He asks the chorus how he can know that the news is true, and not some rumor spread by women that will soon die away.

The chorus says that it has heard a little, but that he should learn the rest from the stranger directly. For, a messenger's report can never be so trustworthy as direct inquiry. Aigisthos announces that he will see the stranger himself and put them to the test. For, no one would be able to deceive Aigisthos, whose mind is quick of sight.

The chorus chants in anxious anticipation, wondering what the outcome of the battle will be. Either everything is ruined, or Orestes will emerge as the golden champion. A servant staggers out of the palace, crying that Aigisthos is dead. He struggles with the door to the women's quarters, wondering whether his cries fall on deaf ears. Where has Clytamnestra gone, he shouts.

Clytamnestra enters, asking what's the matter. The servant replies that the dead are killing the living. She understands the riddle, and recognizes the deceit that has been put upon her. Calling for the servant to bring her an axe, she prepares to fight.

Before the servant can return, the main door opens and we see Orestes standing over the body of Aigisthos. Disgusted over Clytamnestra's sorrow for Aigisthos, Orestes drags her over to his body and prepares to kill her. She stops him by asking whether he has no respect for the breast that fed him as a baby. Orestes hesitates, asking Pylades what he should do. How can he kill his own mother?

Pylades reminds him of Apollo's commands, saying that one should make all men enemies before one offends the gods. Convinced, Orestes turns back to Clytamnestra. He speaks contemptuously to her, saying that she will die next to the man whom she favored over Agamemnon.