What is the summary and the important details in Agamemnon by Aeschylus?

Agamemnon, King of Argos, has been fighting the decade-long Trojan War. As the play opens, a sentinel on the palace watchtower sees a lighted beacon that signifies a victory for the Greeks. While he scurries off to relay the good news to Queen Clytemnestra, members of the Chorus give the audience some background history about the Trojan War, particularly how Agamemnon sacrificed his daughter, Iphigenia, to curry favor with the goddess Artemis. This sacrifice, which occurred well before the play began, becomes the springboard for Clytemnestra’s later actions.
In Greek tragedy, the Chorus serves many functions. Its members provide crucial backstory, running commentary about dramatic events, and frequently making ominous predictions.
As Clytemnestra enters, the Chorus reveals an omen about a child’s death, soon to be avenged. Clytemnestra, who has taken a lover in her husband’s absence, is furious with Agamemnon for killing their daughter and has been plotting his death ever since. When Agamemnon enters with his captive and concubine, the prophetess Cassandra, Clytemnestra pretends to welcome him home, even insisting that he enter the palace on a carpet made of purple robes.
After reluctantly agreeing, Agamemnon enters the palace. In his absence, Cassandra foretells of his death, her own, and the arrival of his avenger. Not long after she joins Agamemnon inside the palace, the Chorus hears him scream in pain. The doors burst open and the audience sees Clytemnestra standing over the bodies of Agamemnon and Cassandra. With the aid of her lover, Aegisthus, she admits to murdering the two to avenge Iphigenia’s death. Aegisthus, Agamemnon’s cousin, has his own reasons for revenge: Agamemnon’s father murdered his brothers.
Although the two lovers have been successful in their coup, the Chorus reveals the name of the one who will avenge the House of Agamemnon: Clytemnestra’s son, Orestes. In doing so, they set the scene for the next drama in the Oresteia Trilogy.