Venice, 1731. Opera is the popular entertainment of the day and the castrati are its reigning divas. 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. The possible suspects could people the cast of one of his operas: a libertine nobleman and his spurned wife, a jealous soprano, an ambitious composer, and a patrician family bent on the theater's ruin. With carnival gaiety swirling around him and rousing Venetian passions to an ominous crescendo, Tito finds that the most astonishing secrets lurk behind the masks of his own family and friends.