On the coast of Tracia lays the body of little Polidoro, son of Priamo and Ecuba, killed during a kidnapping by the king of Tracia, Polimestore, to whom he had been trusted by his parents. Ecuba, still unaware, beg Ulisse not to have her daughter Polissena sacrified on Achilles grave. The scarification, however, is made and a female servant finds, on the shores of the sea, the dead body of Polidoro. Connecting the crime with Polimestore, Ecuba begs Agamennone not to go against her plan of revenge and she attracts Polimestore and his two sons to her tent where she kills the children and blinds the king of Tracia.