Agamemnon is coming back after ten years' exile.
Agamemnon arrives home with the Trojan princess Cassandra. His wife, Clytemnestra, welcomes them in, but Cassandra prophesies that they are about to be killed.
Clytemnestra kills Agamemnon. She is helped by her new lover, Aegisthus, Agamemnon's nephew, whose siblings were murdered by Agamemnon's father, Atreus.