The play begins with Orestes, Agamemnon's son, grieving at his father's tomb. He hides himself when he notices his sister Electra drawing near. She is their to offer libations to the spirit of their deceased father Agamemnon in order to quell the terrible dreams that have been plaguing their mother Clytaemystra, a conspirator in Agamemnon's murder. But Electra is unsure how to offer the libation since its purpose is helping those who committed the dishonorable act of murdering her father. Her attendant offer her the advice to use this libation instead to further enrage Agamemnon's spirit and to bring death upon those who betrayed him.
Orestes then reveals himself to Electra. He explains that Apollo has charged him with the task of taking vengeance against their father's killers. After much talk concerning the dishonor of Agamemnon's death, Orestes reveals his plan to kill the traitors Aegisthus and Clytaemystra. He plans to approach the front gate with the men who are loyal to him as a foreigner bringing news of Orestes' death. Then he will have an audience with Aegisthus wherein he will slay him.
Orestes arrives at the gate and is met by his mother who grieves over the news of her son's death. She invites him and his men in to give the news to Aegisthus directly and to stay the night as repayment for the trouble of bringing the news.
While Orestes and company are waiting Aegisthus is encouraged by Orestes' old wet-nurse (subtly influenced by the attendant who was at the tomb with the siblings) to not take any bodyguards with him. Upon arrival Orestes wastes no time taking vengeance upon his father's murderer. Soon after Clytaemystra happens upon the scene. She begs to be spared out of loyalty to the one who birthed him. But Orestes is reminded that this task comes from Apollo himself. Clytaemystra and Aegisthus are wrapped in the shroud in which Agamemnon had been killed.
Orestes is begged to stay, but he refuses knowing that he cannot find peace in Argos after what he has done, even though ordained by the gods. His mother's hate would haunt him just as Agamemnon haunted her. He leaves to seek refuge far away in Apollo's temple, never to return.
