Different versions of Electra story

Here's a comparative list of how Aeschylus (525 BC), Sophocles (495 BC), and Euripides (480 BC) interpreted elements of the Electra story.

Sacrifice of Iphigenia
Euripides (Iphigenia at Aulis): Agamemnon has second thoughts about whether he can go through with the sacrifice of his daughter. His brother Menelaus is enraged and convinces Agamemnon that hesitation would lead the army to mutiny and bring about the downfall of Greece. Iphiginia is thrilled at the prospect of marrying Achilles but she and Clytemnestra eventually discover the truth. Achilles is furious at having been used as a prop to lure the women to Aulis, and he vows to protect Iphigenia. They try in vain to change Agamemnon’s mind, but he believes he has no choice. Iphigenia has a change of heart and decides that the heroic thing to do is to die a noble death for her country. A messenger arrives after the sacrifice to inform Clytemnestra that at the last minute, the goddess Artemis switched Iphigenia’s body with a deer and the gods swept Iphigenia off to Tauris. This does not pacify Clytemnestra, who still considers her daughter to be in the hands of the gods and lost to her forever.

Murder of Agamemnon
Aeschylus (Agamemnon): Agamemnon returns victorious from the ten-year war, after plundering and ravaging Troy, with Trojan prophetess Cassandra as his concubine. The chorus notes that justice came at a great price. Clytemnestra greets Agamemnon by falsely maintaining her fidelity and persuading him to walk into the palace on crimson tapestries fit for the gods. Cassandra cries out insanely to Apollo and utters prophecies about infanticide, fatal baths, and a murderess in the house. She also predicts that a son will turn to murder the mother who had murdered his father. Cassandra enters the house, and Clytemnestra murders her and Agamemnon, and assumes the throne with her brother-in-law and lover Aegisthus. She justifies her actions to the Chorus and professes herself to be an instrument of divine justice.

Murder of Clytemnestra
Aeschylus (The Libation Bearers): Clytemnestra has a nightmare in which she gives birth to and breastfeeds a serpent. She orders Electra to mourn and pour libations on Agamemnon’s tomb to make amends. There Electra meets and recognizes Orestes, returned from exile with his friend Pylades. They appeal to Apollo, who encourages them to murder the usurpers, and they invoke the spirit of Agamemnon to work themselves into a frenzy so that Orestes may go through with matricide They enter the palace pretending to bear news of Orestes’s death, and when Clytemnestra calls in Aegisthus to share the news, Orestes comes out and murders them both. Orestes is immediately beset by Furies, visible only to him. He runs out of the palace in a fierce fit of madness, and the Chorus wonders whether the curse on the house of Atrius will ever be lifted.

Sophocles (Electra): Electra hears about Orestes’s return from her sister Chrysothemis, but refuses to believe it and tries unsuccessfully to implicate her sister in a murder conspiracy. Orestes in disguise arrives with an urn supposedly containing his ashes, then reveals himself to Electra upon recognizing her. They murder Clytemnestra first, then show her body to Aegisthus before carrying him away to be slaughtered in the same place as Agamemnon.

Euripides (Electra): Orestes and Pylades conceal their identities when visiting Electra and her husband, but an aged servant recognizes Orestes by a scar. The siblings conspire. The servant lures Clytemnestra to Electra’s house by telling her that Electra has had a child. Orestes goes off to kill Aegisthus and returns with his body. His resolve wavers at the prospect of patricide but Electra coaxes him into going through with it. The two of them kill Clytemnestra by pushing a sword down her throat, and both feel oppressive guilt. Clytemnestra’s deified brothers appear to tell the siblings that their mother received just punishment, but the matricide was still a shameful act and the siblings must atone and purge their souls of the crime. They also decree that Electra marry Pylades and that Orestes be persecuted by the Furies.

Orestes’s Guilt
Aeschylus (The Eumenides): The Furies continue to torment Orestes and follow him into the wilderness. Orestes begs Apollo to drive the Furies away, but he is powerless to do so. He directs him to the temple of Athena, who declares that there must be a trial. The jury is split, and Athena casts the deciding vote acquitting Orestes. She renames the Furies the Eumenides, the kindly ones, and announces that mercy should take precedence over vindictiveness. Orestes returns to Greece to assume his place as king, and his punishment is complete.

End of the Curse
Euripides (Iphigenia at Tauris): Iphigenia is the high priestess of Artemis, and her role is to sacrifice Greek strangers who come to Tauris. She interprets a dream she had as meaning that Orestes is dead and she is the last remaining member of her family. Orestes and Pylades appear, and Orestes recounts that after praying to Apollo to drive away the Furies that have followed him all over Greece and driven him to madness, Apollo sent him to Tauris to steal a statue of Artemis, which will purify Orestes and end his suffering. The two are captured but Iphigenia recognizes them. The three of them steal the statue and escape.