Venice, 1731. Opera is the popular entertainment of the day, and the castrati are its reigning stars. Tito Amato, mutilated as a boy to preserve his enchanting soprano voice, returns to the city of his birth with his friend Felice, a castrato whose voice has failed. Disaster strikes Tito's opera premier when the singer loses one beloved friend to poison and another to unjust accusation and arrest. Alarmed that the merchant-aristocrat who owns the theater is pressing the authorities to close the case, Tito races the executioner to find the real killer.