After a stormy voyage, Agamemnon and Cassandra landed in Argolis or were blown off course and landed in Aegisthus' country. Clytemnestra, Agamemnon's wife, had taken a lover, Aegisthus, and they invited Agamemnon to a banquet at which he was treacherously slain.

According to the account given by Pindar and the tragedians, Agamemnon was slain by his wife alone in a bath, a blanket of cloth or a net having first been thrown over him to prevent resistance. Clytemnestra also killed Cassandra. Her wrath at the sacrifice of her daughter Iphigenia, her jealousy of Cassandra, and the Greeks having gone to war for Helen's affection, are said to have been the motives for her crime.

Aegisthus and Clytemnestra then rule Agamemnon's kingdom for a time, until his murder is eventually avenged by his son Orestes, now grown, with the help of his sister Electra.