Euripides 
Hecuba 

In the play’s unconventional opening, the ghost of Polydorus tells how when the war threatened Troy, he was sent to King Polymestor of Thrace for safekeeping, with gifts of gold and jewelry. But when Troy lost the war, Polymestor treacherously murdered Polydorus, and seized the treasure. Polydorus has foreknowledge of many of the play’s events and haunted his mother’s dreams the night before.