The Oresteia.

The Oresteia -- Agamemnon, Choephori, and The Eumenides -- depicts the downfall of the house of Atreus: after King Agamemnon is murdered by Clytemnestra, their son, Orestes, is commanded by Apollo to avenge the crime by killing his mother, and he does so, bringing on himself the wrath of the Furies and the judgment of Athens. Together, the three plays are one of the major achievements of Greek antiquity. - Publisher.