The play opens at Mycenae before the palace of Agamemnon. At daybreak, Pylades, Orestes, and Paedagogus, Orestes's keeper, enter as if from foreign lands. Paedagogous introduces Orestes to the city of Orestes's fathers and urges a start to the action for which they have come, namely, the vengeance of Agamemnon's death. Orestes replies by recalling the oracle of Apollo, which has called for such vengeance, and by describing the manner in which he plans to execute the revenge. Paedagogus is to go inside the palace and relay the false report that Orestes has been killed in a chariot race. Meanwhile, Orestes and Pylades will make an offering at Agamemnon's grave, as instructed by Apollo, before returning to the palace with an urn supposedly containing Orestes's ashes. Orestes ends his speech with a prayer to the gods and to his father's house. Electra, meanwhile, can be heard sobbing within the house. Orestes expresses the desire to greet her immediately, but Paedagogus insists that nothing should precede the work of Apollo, and that the next step must be to perform Agamemnon's libations. Paedagogus, Pylades, and Orestes exit the stage. Meanwhile, Electra enters from inside the palace.
Electra, alone on stage, sings a monody of grief. She details her suffering and her constant mourning over the murder of her father, Agamemnon. He was murdered by Electra's mother, Clytemnestra, and Clytemnestra's lover, Aegisthus, when Agamemnon returned after many years fighting in a foreign land. She calls on the furies and the gods of the underworld to help her avenge her father's death by sending her brother, Orestes, back to her; she feels she cannot achieve revenge alone.
The chorus, consisting of the virgins of the place, approaches Electra to give her consolation. The chorus beseeches Electra not to waste her life away in mourning, and although Electra expresses thanks for their concern, she insists that she cannot let go of the memory of her father, nor of her mourning. The chorus reminds Electra that grieving will do nothing to bring her father back from the dead, that her sister Chrysothemis has persevered, continuing on with her life, and that there remains the possibility that one day Orestes will return to his homeland. Electra proves inconsolable. She describes how she wanders through her father's halls as a slave, forced by her mother to dress in rags and eat meagerly. She condemns her mother's lust and corruption and acknowledges that she feels utterly compelled, as if by a force greater than herself, to avenge her father's death.
Electra gives faint hearing to the encouraging arguments of the chorus. She apologizes to the chorus for the extremity of her grief, but explains that in the name of justice and honor she has no choice but to mourn her father's death and desire its revenge. She describes her hateful relationship with her mother and the pain she feels at seeing Aegisthus wearing her father's robes, standing at her father's hearth, and lying in her father's bed next to Clytemnestra. She tells of Clytemnestra's anger towards Electra at the mention of Orestes, whom Electra herself smuggled from the kingdom as a child so that he might be spared a life among corruption and evil. She concludes her speech by stating her firm hope and belief that one day, Orestes will return to her and help avenge their father's murder.
A Greek tragedy is usually divided into three parts: the prologue, or introduction of the play's situation and circumstances, the parodos, or entry song of the chorus, and a series of episodes, or scenes, divided by choral songs called stasima. A lyric duet between the chorus and one or more characters is called a kommos, and the final episode is often called the exodos. Section one of this SparkNote consists of the prologue and kommic parodos. The prologue itself consists of two parts, the first being a dialogue in iambics, the common meter of speech, spoken between Orestes and Paedagogus, or the Old Man, and the second being a monody sung by Electra in the verse meter of lyrical anapests.
The prologue is striking because it explores the psychologies of both Orestes and Electra, the two characters in the tragedy for whom revenge is most important. As Orestes describes in his opening speech the manner in which revenge is to be exacted, according to the oracle of Apollo, he reveals a certain level of uneasiness at the prospect of lying about his own death. He reassures himself that there is no harm in the lie as long as it pays off at the end. This cheap language concerning politics and expediency, as well as the details of his lie (that he has been killed in a chariot race), suggest his immature perspective, limited by privilege. Orestes's language implies that perhaps Orestes does not fully comprehend the magnitude of what he has taken on, namely, the murder of his mother and her lover.
The mundane and dialogical first half of the prologue that deals with Orestes sharply contrasts with the lyrical and passionate second half, in which Electra sings her mournful monody. As evidence of her heightened emotion, she speaks not about things, as Orestes does, as much as to them: she calls on light, air, Hades, and Persephone as witnesses to her misery and as potential aids in exacting revenge. She addresses her father, too, expressing the depth of her pity at his unjust murder. Orestes, by contrast, demonstrates little emotion and speaks of it even less; nor does he address his feelings about his father's death. Orestes, it seems, has been driven to revenge more by Apollo's oracle than by deep emotion, unlike his sister, who is driven by her heart.
The parodos, or the song by which the chorus is introduced, is a lyric dialogue, or kommos, between Electra and the chorus. The chorus in a Greek tragedy is traditionally suspect of heightened emotion and accordingly they emotionally beseech Electra. Electra's response that she feels forced to act as she does—seemingly regardless of whether or not she actually wills it—demonstrates a high level of self-awareness on the part of the heroine and suggests that perhaps, just as Orestes might not comprehend quite what he has undertaken, Electra does not wholly approve of what she feels she must do. She invokes the concepts of justice and reverence again and again, as if she is the agent by which these fallen values might be restored, by whatever required brutal means.