The scene is laid in Mykene.
In the opening scene five maids are talking about Elektra, who enters haggard and in rags, shunning them and disappearing again like a hunted animal. Day by day she mourns for her father Agamemnon, who has been murdered by her mother's lover Aegisthos.
The maids find fault with Elektra's strange behaviour and haughtiness. They believe her to be dangerous and suggest, that her mother should lock her up safely. One maid reproves them however. She respects in Elektra the dead King's cherished daughter, who, though in rags and brought so low by her unnatural mother, that she is compelled to eat with the servants, yet bears herself more queenly than Clytemnestra herself. The others beat their companion for her allegiance to Elektra, who appears again, moaning for Agamemnon. His poor murdered body seems to arise fresh before her every day. Her one aim in life is vengeance on his murderers, and her only hope is her brother Orestes, who has disappeared.
She is joined by her sister Chrysothemis, who implores her to abandon her vindictive thoughts, the cause of their common captivity. She further reveals to her, that their mother means to imprison her, but Elektra laughs at her terror.—Chrysothemis longs for freedom, the love of a husband and children, and is utterly alien to her sister's dark thoughts. Hearing her mother's step she entreats Elektra to go away, Clytemnestra having had evil dreams about her son's coming home and killing her. Elektra, regardless of her prayers meets her mother with a cruel stare. The latter is in her darkest mood, which grows worse at her hated daughter's appearance. But Elektra, accosting her as a goddess for once quiets her suspicions. Clytemnestra dismisses her servants, who tries to warn her against her daughter. When they are alone, the Queen complains bitterly of the frightful dreams that haunt her, and wants to know, what she can do to banish them.
Elektra answers enigmatically, that a woman must be sacrificed, and that a man, but not Aegisthos the coward, must do it.
Clytemnestra, vainly guessing at his name, is reminded of her son Orestes, whom the mother has made to disappear, while he was a child. Her troubled looks convince Elektra that Orestes is living, and casting off her disguised mood, she sternly tells her mother, that she herself is to be the sacrifice.—In a long wild monologue she reproaches her for all her treachery, ending by depicting the awful fate that awaits her, and rejoicing over it.
Clytemnestra's terror is appeased by the appearance of her attendants, one of whom whispers to her the welcome news of Orestes' death.
Wildly triumphant she leaves her daughter, who hears the bad news from Chrysothemis. Elektra will not believe it until she hears it from another servant, who is sent into the fields, to inform Aegisthos about it. Then she implores her sister's help in killing her mother and her lover, while they are asleep.—She has hidden the axe, with which her father was slain, yet being physically weaker than her younger sister she requires assistance. But although she promises her all the good things on earth and is ready to serve her like a slave, Chrysothemis turns from her shuddering and finally escapes. Elektra wildly curses her and resolves to carry out her design alone.
For this purpose she unearths the axe, but is disturbed by the arrival of a stranger, who takes her for one of the maids. He replies to her angry questions, that he has come to announce Orestes' death, which he has witnessed. Flashing with anger Elektra reproaches him for not having died in his stead. Her bearing convinces him, that she is superior to what she seems. Then she tells him, that she is Elektra, to which he replies in a whisper: "Orestes lives."—At this moment an old family servants enters, bringing three others, who, falling at the stranger's feet, hail him as their master. Then Elektra recognizes her brother and greets him with passionate joy, though she is ashamed of her own miserable appearance. Orestes at once agrees to help her in her vengeance and enters the house with his old servant, locking the door behind him. Elektra, standing erect on the threshold, hears Clytemnestra's scream and exclaims: "Hit her once more!" Those screams bring on Clytemnestra's servants together with Chrysothemis, all trying to open the closed door. But when they see Aegisthos returning they vanish.