The scene of the play is an undefined space in front of Agamemnon's palace in Argos, with a tower in the background. On the top of that tower is a Watchman. He begs the gods to deliver him from his yearlong task of watching all night long, every night. He is watching, as Agamemnon's wife, Clytemnestra, who thinks like a man, has ordered, for the beacon fire that will signal that the Greeks have taken Troy. He keeps himself awake by singing and by weeping for the disorder in the house (that is, the royal house, the family of the kings), and he hopes for the fire that will bring good news.
He sees the fire, and cries out in joy at the light that will have the citizens of Argos dancing in triumph. He goes to tell Clytemnestra the news, praying that the lord of the house, Agamemnon, really will come back and he can take in his own his master's loved hand. He will say nothing more about the situation in the house (an ox is on his tongue, as he expresses his inability to say more); if the house could speak, it would have a tale to tell.
The Chorus enter, old men of Argos who are helping the queen govern as members of the Council. As they enter and march around the space, they chant:
It is now ten years since the Menelaus and Agamemnon, sons of Atreus and rulers, Menelaus of Sparta and Agamemnon of Argos, led the Greeks against Troy, like vultures robbed of their young who lament, and some god hears them and sends the Fury against those who have robbed the nest. So Agamemnon and Menelaus are sent by Zeus against Paris for his violation of the sacred bond between host and guest in the stealing of Helen from Menelaus when Menelaus was his host. Yet all that suffering and death for one woman! Well, it will go as it will, and we who were too old to go with the army stay here, with no strength in us, leaning on staffs.
They then face the palace and ask Clytemnestra (who is not present) why she has sent for them and why she has ordered sacrifices on all the altars of the city. Then they sing and dance the first choral ode of the play. They tell how, before the ships sailed from the port of Aulis, an omen came-two eagles tearing apart the body of a pregnant hare. The seer Calchas read this as an omen that the two sons of Atreus would destroy Troy, but prayed that it was not also an omen of ill. Artemis loves the young of all beasts and so must hate the slaughter of the hare. May she not send adverse winds, Calchas prayed, leading to the need of a horrible sacrifice that will lead to hatred within the family.
The refrain of this part of the song of the Chorus is, "Sing sorrow, sorrow, but may the good prevail." The song then continues with a prayer to Zeus. The first ruler of the universe, Ouranos, was defeated by Kronos, and Kronos by Zeus, whose victory all should hail. Zeus has ordained that men learn by suffering.
Despite Calchas's prayer, the Chorus sing, adverse winds did hold back the Greek force day after day, and Calchas finally told them that the only way to appease Artemis, who had sent the winds, was for Agamemnon, the main leader of the army, to sacrifice his daughter Iphigeneia. Then Menelaus and Agamemnon wept, and Agamemnon, in agony at the thought of sacrificing his daughter, yet in worse agony at the thought of betraying the army, chose to sacrifice. The Chorus are horrified by his choice, seeing him as ruthless, infatuated, committed to an evil deed. They sing as though they are seeing it-Iphigeneia in her innocence and beauty, gagged so that she would not put a curse on the house, appealing with her eyes for mercy. Of the actual deed of sacrifice they do not sing, nor of the hatred within the family that deed has in fact led to. They end with a foreboding of more suffering, and a prayer that all may somehow turn out well, as Clytemnestra, who has guided our land in the king's absence, wishes.
The Agamemnon is the first play of a trilogy, the whole of which is known as the Oresteia. Written in fifth-century BC Athens, the Oresteia retells an ancient story from the time of the Trojan War, a story of vengeance taken by individuals: the king who led the Greeks against Troy, Agamemnon, who had sacrificed his own daughter in order to get favorable winds for the voyage to Troy, was killed by his wife Clytemnestra and her lover Aegisthus when he returned home; his son Orestes then killed his mother. Aeschylus retells the story in such a way that it becomes a story of society moving from justice carried out by vendetta, by exacting blood for blood, to justice carried out by courts of law in which the rights and wrongs of a deed are argued. Another prominent theme of the play is the tension between men and women, with a strong implication that men are blinded by their own beliefs about women.
As a first step in this story, the Agamemnon shows the full horror of blood-for-blood vengeance, not only by telling of Clytemnestra's killing of her husband, but by recalling all the causes of that murder, all the wrongs, ancient and recent, that have woven the net of circumstance in which Agamemnon is trapped. It is the most tragic, in our sense of the word, of the three plays, and is often performed singly, without the other two plays in the trilogy. But it is well to remember, as one reads it, that the ending of the whole trilogy is a celebration of a new age of law and justice, in which the Furies become the Eumenides, the Kindly Ones.
The Furies are a constant presence in the play, sometimes referred to collectively as "the Fury." (In the scene summarized above, Menelaus and Agamemnon are seen as driven like the Fury against Troy.) The Furies, or Erinyes (Curses) in Greek, are cthonian deities-deities associated with Earth. These particular chthonian deities are the Avengers, sometimes seen as daughters of Earth, sometimes as daughters of Night, who punish crimes against blood kin (especially parents), breaking of oaths, violation of the guest-host bond, and injury to suppliants. Thus Menelaus and Agamemnon play the role of the Fury when they attack Troy, punishing Paris's violation of the guest-host bond, which in Homeric Greece, as in most premodern societies, was seen as sacred.
But mortals who play the role of the Furies, though they see themselves as agents of justice, seem inevitably to be led to commit crimes as bad or worse than those they are avenging. The Chorus say that Artemis was angered by the slaying of the pregnant hare;
the common interpretation is that she was angered by what that slaying stood for-the destruction of Troy, with all its innocent women and children. Therefore she demanded that Agamemnon must first, before he could sail to Troy, bring about the death of his own innocent child, that he must suffer as he was going to make others suffer, and at the same time make his own death at the hands of the outraged mother of his child inevitable. The bitter irony of the Chorus's hope that all may turn out well, as Clytemnestra wishes, is obvious-we may imagine that she has already entered as they speak that hope.