The scene is the throne room of the palace. "An awe-inspiring, blood-smeared statue of Zeus occupies a prominent position." The sun is setting.
Electra has snuck Orestes into the palace. She hides him as two palace guards pass them in the hallway.
The guards are discussing the flies, which they think are worse than ever on account of all the dead roaming around.
They hear a creaking and are convinced it is Agamemnon, come back to sit on his throne.
One of the soldier reckons that, if dead flies come back, too, then the air must be teeming with the little creatures.
As the soldiers investigate the room, Orestes and Electra escape detection and remain in hiding.
King Aegisthus enters with the Queen and orders all the soldiers away.
He and his wife discuss the fiasco earlier that day at the temple; Aegisthus reveals that he played on the fear of the townspeople to keep them in line.
He apologizes to Clytemnestra for what he did to her daughter, and admits that after fifteen years he's tired of forcing remorse on everyone.
Yet he maintains that no man in Argos is sadder than he.
Aegisthus worries aloud about the dead roaming around until Clytemnestra gently reminds him that, actually, he's the one who invented that whole story to "impress [his] people." Remember? Oh right, says Aegisthus. He orders his wife to leave him alone.
Now alone, Aegisthus speaks to the statue of Zeus. He claims he is an empty shell, "more dead than Agamemnon."
He is not sad, since "neither sad nor gay is the desert, a boundless waste of sand under a burning waste of sky."
He's not sad; he's sinister. And he wishes he could cry, but he can't.
The real Zeus enters.
Aegisthus doesn't recognize him and threatens to have the god thrown out as an intruder. Zeus flashes some lightning to reveal his true identity.
Aegisthus claims that he has paid Zeus through his fifteen years of remorse.
Zeus reminds him that no matter how much you repent, it is never enough.
When Aegisthus complains that the task he's undertaken is killing him, Zeus tells him to stop whining; he's got at least another twenty years left.
The King is not happy to hear this. He would rather die.
In that case, says Zeus, what would Aegisthus do if a man ran towards him at this very moment baring a sword?
Aegisthus isn't sure what he would do. Well, says Zeus, dying isn't a good idea, since Aegisthus will be tortured in hell for all eternity.
By the way, continues Zeus, Electra and Orestes are coming to kill him tonight.
The King isn't particularly outraged. That's the natural order of things, he figures, and there's nothing he can do about the revenge Agamemnon's children rightfully seek.
Zeus responds that, actually, yes, there is something the King can do: he can have Electra and Orestes thrown into a dungeon.
But the King refuses; he is too tired to fight back, even though his refusal means defying the order of the gods.
Zeus finds this resistance amusing, and condescends to his "little rebel."
Aegisthus might make a show of defiance, but in his heart he has already said yes to Zeus's orders. Zeus wants the crime averted; therefore it will be averted.
The King wants to know if Zeus similarly warned Agamemnon of his impending death.
No, says Zeus, since Agamemnon wasn't as dear to him as Aegisthus is.
But Aegisthus believes that Zeus is actually trying to protect Orestes here. He suspects that the god is concerned with preserving the young man's innocence, not the old man's life.
Zeus maintains that this is not the case. He explains that not all crimes (like Agamemnon's murder as opposed to Aegisthus's) are equal in his eyes.
Then Zeus comes clean.
He admits to committing the first crime. He chose to make man mortal, which amounted to basically murdering everyone. When men murder, therefore, they're not killing one another so much as they're hastening the death that's already on its way.
Zeus reveals that, had Aegisthus not killed Agamemnon, the latter would have died of natural causes a mere three months later.
The reason Zeus let the murder happen is that it meant Aegisthus and his people would be atoning for it for the rest of their lives. A people trapped in misery and penitence pleases the gods.
Finally Aegisthus realizes what this is all about.
If Orestes kills him, the young man will feel no remorse. A remorseless crime is no good for Zeus and the other gods.
Correct, affirms Zeus.
King Aegisthus again refuses to prevent the crime.
Zeus explains that he made kings on earth in his own image, and that, like it or not, no matter how much Aegisthus hates him, he has to admit that he is similar to Zeus.
He goes on to claim that both of them "harbor the same dark secret in [their] hearts" – "the bane of gods and kings" – "the bitterness of knowing men are free."
(This point about freedom is an important one – we'll return to it later.)
Aegisthus is shocked that a god would compare himself to a mortal. Since he took the throne of Argos, he says, he's been trying to build up a fearsome image of himself before his people. Now, this false image is all he sees when he looks at himself. He has lost his sense of personal identity, and wants to know if he is anything else besides the dread he inspires in his people.
Zeus points out that he has the same problem himself. He indicates the blood-smeared statue of his likeness and says that that image has become his entire being.
Zeus and Aegisthus are both doomed: they have an insatiable passion for order.
Aegisthus agrees. The longing for order is why he committed that crime against Agamemnon fifteen years ago.
Zeus again commands the King – this time in the name of order – to lock up Orestes. He claims the young man is dangerous because he knows he is free.
If Orestes knows he is free, says Aegisthus, then locking him in chains won't help. Why doesn't Zeus strike him down with a thunderbolt?
Because, responds Zeus, once a man knows he is free, the gods are powerless against him.
Fine, says Aegisthus, he will act according to Zeus's will.
Just after he leaves, Electra and Orestes come out of hiding. She bars the door while her brother approaches the King.
Orestes commands the King to draw his sword and defend himself, but Aegisthus refuses; he would rather die.
Orestes sighs and strikes the man down with his sword.
As he dies, Aegisthus asks Orestes if he feels any remorse.
No, says Orestes, why should he? He's "only doing what is right."
Aegisthus doesn't think so, since Zeus commanded that Orestes not kill the King.
But the gods don't determine justice, counters Orestes. It is a matter between men. It's his own job to kill Aegisthus and return to the people of Argos "their sense of human dignity."
Aegisthus moans and writhes in pain, which disturbs Electra, who finds death an ugly sight.
The King curses both of them, and finally Orestes strikes him again.
Aegisthus delivers his final line: "Beware of the flies, Orestes, beware of the flies. All is not over."
Orestes kicks the dead body and tells Electra to lead him to the Queen's bedroom.
Electra is shocked at his attitude. Why kill Clytemnestra when she can do no more harm?
She notes the remarkable change that has come over her brother since he first arrived in Argos.
Orestes doesn't want to stand around and talk. If Electra won't show him where the bedroom is, he'll find it himself.
Now Electra is left alone with Aegisthus's dead body. She wonders aloud if her mother will scream when Orestes kills her, but reasons that she (Electra) must want this to happen.
Then she looks at the dead body.
Electra used to hate Aegisthus, but now that he's dead, her hatred is dead too. She can't bear looking into his open eyes, so she covers them up.
Then the sound of Clytemnestra screaming echoes down the hallway.
Electra has wanted this for years, and now that it's happened her "heart is a lump of ice."
She tries to convince herself that she's happy this all happened.
Orestes enters, his sword covered in blood.
Electra throws herself into her brother's arms and claims that she's joyous.
She wants to know if the Queen begged for mercy.
Orestes makes it clear that he's not sorry for what he did. "There are some memories that one does not share," he says, so he won't give her the details.
But Electra pushes. Did Clytemnestra die cursing them? Yes, says Orestes, she did.
Orestes claims that a new day is dawning, that he and Electra are now free. Yesterday he had nothing, but today she belongs to him.
Electra looks at him closely; he looks different, she says.
He explains that "freedom has crashed down on [him] like a thunderbolt" and so changed him.
But Electra doesn't feel free. She's a concerned that they've just killed their mother and can't undo it.
Orestes doesn't want to undo it – it was a good deed, he says.
He is happy to carry the burden of this murder, as that burden is his freedom. Yesterday he felt aimless, as though he had no path, but today he has his own direction to travel.
But Electra isn't listening.
She claims she can't see anymore and that her brother's voice is cutting her like a knife.
Suddenly Electra cries out – she sees thousands of "them" swarming all around her, beating their wings.
Orestes thinks she's talking about the flies, but Electra responds that the flies are the Furies, the goddesses of remorse, and that they will never leave the two of them alone.
Just then voices come from the hallway outside. The Queen's cries of death summoned the guards.
Orestes takes Electra and heads for the shrine of Apollo, to spend the night there "sheltered from men and flies."