The play begins in the main square of the sunbaked city of Argos. A huge, blood-smeared statue of Zeus stands center. Fat, disgusting flies are everywhere and screams echo. Orestes and his tutor arrive. Fifteen years ago, Clytemnestra, the mother of Orestes and Electra, and her lover Aegistheus had killed their father, Agamemnon. Aegistheus wanted to kill Orestes, but the boy managed to escape. And now, brought up in distant Athens and raised by a wealthy family, Orestes returns to his hometown. Zeus enters, disguised as a city dweller. He explains to Orestes, who calls himself Philebus and claims to be from Corinth, that today is the day of the dead, and the cries mean that the ceremony has begun: the inhabitants of the city, headed by the king and the queen, repent and pray their dead to forgive them. The dead flow out of a tomb where they are kept and return to their old houses to remind the people of their heavy remorse.
Zeus tells Orestes that local inhabitants are great sinners, but they have embarked on the path of redemption. Orestes should leave them alone and treat them with respect for the pain that they have taken upon themselves.
Zeus leaves. Orestes is at a loss: a city where he could rightly be a king is a stranger to him and he does not have a place in it. Orestes decides to leave. Before doing so, Electra appears. She doesn’t notice the newcomers and curses the statue of Zeus. When she sees Orestes and the tutor, she is startled but then claims she is not frightened. When Orestes (who is still going by Philebus) hears her name, he dismisses the tutor.
Electra tells this stranger about her hatred of Clytemnestra and Aegistheus. They treat her terribly and she is forced to be a servant. She is alone and does not have friends; however, she lives with hope because she is waiting for one person to return.
Clytemnestra enters. She asks Electra to put on mourning clothes because the official ceremony of repentance will begin soon. Noticing Orestes, Clytemnestra is surprised because travelers, as a rule, avoid Argos because they see this repentance as a plague and are afraid of infection.
Electra mockingly warns Orestes that publicly repenting is the national sport of the Argives, but everyone already knows each other's crimes. She adds that the crimes of the queen are official crimes, which can be said to be at the basis of the state system. Every year on the day of the murder of Agamemnon, the people go to the cave. The huge stone that closes the entrance is pushed aside, and the dead, as they say, rise from hell and scatter around the city. However, Electra announces she is not going to take part in these stupid games because they are not her dead. Clytemnestra tells her that if she does not obey she will be brought by force. Electra finally agrees to attend.
Electra leaves. Clytemnestra also departs, but tells Orestes he should leave the city. Zeus returns and offers Orestes a pair of horses at a fair price. Orestes responds that he changed his mind and will stay.
The people crowd in front of a closed cave, grumbling that the royals are slow to appear. Aegistheus and Clytemnestra appear. They throw away the stone, and Aegistheus, standing in front of the black hole, turns to the dead with a penitential speech.
Suddenly Electra appears in a blasphemous white dress. She calls people to stop repenting and start living with simple human joys. They ought to let the dead live in the hearts of those who loved them, but do not drag them to the grave. Zeus is annoyed with her, and watching from afar, causes a block that closed the entrance to the cave to roll down with a crash. The crowd, which had been intrigued by her words, now grows stiff with fear. Aegistheus stops the angry people from harming Electra, reminding them that the law prohibits punishment on the day of the holiday. He tells her she is banished.
Everyone leaves. Orestes approaches Electra, who desires revenge. He tells her who he is and suddenly experiences an epiphany that he is a completely free man. Electra is disconcerted by his behavior but comes to embrace him when he righteously declares he will murder Agamemnon’s killers and take on the burdens of the people.
In the throne room of the palace stands a terrible bloodstained statue of Zeus. Orestes and Electra hide near it. Around it are the flies. Clytemnestra and Aegistheus enter, both tired of their own invention. The queen leaves and Zeus comes to Aegistheus. He reveals his identity and that Orestes plans to kill Aegistheus. Aegistheus does not care and is ready to die. Zeus disapproves of this and knows that while he cannot touch the free Orestes, something must be done so this idea of freedom does not spread. He tells Aegistheus to take care of it, and exits.
Out of the darkness Orestes jumps out with a drawn sword. He offers Aegistheus to defend himself, but he refuses. Orestes kills the king, and then rushes to the queen's room. Electra looks at the body of Aegistheus and wonders if she truly wanted this. She hears Clytemnestra cry out and feels only fear. She tries to tell herself that this has been her dream and she is elated. Orestes returns and announces the queen is dead. He feels no remorse whatsoever. Electra is scared but claims she is happy.
However, she notices the flies and that they are actually the Furies. The two plan to stay in Apollo’s shrine as a refuge, and Orestes will speak to the people.
Swarms of flies surround the brother and sister as they sleep. The Furies delight in these victims before them, planning their destruction.
Orestes and Electra awake. Looking at his sister, Orestes discovers that during the night she became remarkably similar in appearance to Clytemnestra because she, like her mother, witnessed a terrible crime.
The Furies cackle and dance, circling around Orestes and Electra. Electra regrets what she did, but Orestes persuades his sister not to repent. He feels completely free because he assumes all responsibility for himself.
Zeus enters and tries to pacify Electra; he just needs a drop of remorse. Zeus convinces Electra that she did not want to kill, and that just as a child she always “played” a murder because in this game one can play alone. Electra seems to begin to understand herself.
Zeus asks Orestes and Electra to renounce the crime, and then he will put them on the throne of Argos. Orestes answers that he already has the right to this throne.
Zeus notices that now all the inhabitants of Argos are waiting for Orestes near the exit from the sanctuary with pitchforks and clubs. Orestes will not confess his guilt, especially as Zeus himself created a man free. Orestes concludes there is neither good nor evil in heaven, and there is no one who can command him.
However, Orestes realizes his freedom means expulsion. Zeus silently withdraws. Electra feels tortured but she leaves Orestes, and as soon as she steps out she is attacked by the Furies. She calls to Zeus that she repents, and the Furies back away from her.
The Furies focus all their attention on Orestes now. The doors in the sanctuary swing open, and behind them is a furious crowd ready to tear Orestes to pieces. Addressing the citizens, Orestes proudly declares that he takes responsibility for the murder. He committed it for the sake of people: he took upon himself the crime of a man who could not cope with his burden and shifted responsibility to all residents of the city. He announces that the citizens must try to start anew.
Orestes walks through the parted crowd of citizens. As he leaves them, the flies follow. The Furies pursue him with terrible screams.
