The play open a few days after the closing scene of The Choephori, outside the Temple of Apollo at Delphi The Priestess of Apollo enters, chanting a prayer to the various divinities that have been associated with the holy shrine of Delphi. Fourth and last in the succession at the sanctuary is Apollo. He has been entrusted with the secrets of prophecy and has been assigned this oracle as the spokesman of his father Zeus.
The priestess goes into the temple. There is a short pause, then she rushes out in terror. She describes the horrible sight she has just seen — a man covered with bloodstains and holding a bloody sword is kneeling at the altar stone in the posture of a suppliant; asleep on the floor around him are gathered a group of revoltingly ugly creatures dressed in black. The priestess says that this matter is so mysterious that only Apollo himself can unravel it. She exits.
The recitation of mythological history by the priestess describes the clash between the old and new (Olympian) gods and is the first step in the generalization of Orestes' predicament into a conflict between old and new conceptions of justice.