For a three-act plot analysis, put on your screenwriter’s hat. Moviemakers know the formula well: at the end of Act One, the main character is drawn in completely to a conflict. During Act Two, she is farthest away from her goals. At the end of Act Three, the story is resolved.
Act I
Orestes and the Furies wake up in Delphi and get sent to Athens by Apollo and the ghost of Clytemnestra, respectively.
Act II
The Furies catch up to Orestes in Athens, but the goddess Athena appears and organizes a trial, with Athenian mortals as jurors, the Furies as prosecuting attorneys, and Apollo as Orestes's defense attorney.
Act III
Orestes is acquitted and goes home to Argos; Athena transforms the Furies into benevolent helpers of good people and punishers of evildoers. Their new name is the "Kindly Ones" or "Eumenides."