Electra

Her brother, Orestes, was hounded by the Furies for killing Clytemnestra, their mother, who conspired with her lover to kill King Agamemnon, their father, and his concubine, Cassandra, in revenge for the king's sacrifice of Iphigeneia, their sister, to the goddess Artemis, leading to the Trojan War and Oreste's eventual acquittal by the goddess Athena.  Where was Electra? There all along. Along for the ride.