Cry to Heaven is a novel by American author Anne Rice published by Alfred A. Knopf in 1982. Taking place in eighteenth-century Italy, it follows the paths of two unlikely collaborators: a Venetian noble and a maestro castrato from Calabria, both trying to succeed in the world of the opera.

Set in eighteenth-century Italy, Cry to Heaven focuses on two characters, peasant-born Guido Maffeo, who is castrated at the age of six to preserve his soprano voice, and fifteen-year-old Tonio Treschi, the last son of a noble family from the Republic of Venice, whose father, Andrea, is a member of the Council of Three of La Serenissima. Although Guido becomes a star of the opera as a teenager, he loses his voice at eighteen, as many castrati did. After a suicide attempt, he becomes a music teacher in the Naples conservatorio. Tonio, on the other hand, learns that his older brother Carlo was exiled for embarrassing the family. Although Andrea attempts to cut Carlo out of the family, Carlo returns after Andrea's death, and plots to regain his original position. Revealing that Tonio is actually his illegitimate son, he has Tonio castrated, and sends him off with Guido to study in Naples.

Although everyone in Venice is inclined to believe that Carlo was behind his castration, Tonio cannot accuse him of the crime because doing so would result in the extinction of the Treschi family. After some soul-searching, he decides to remain in Naples and study under Guido, holding off on revenge until after Carlo and his mother (also Carlo's lover and later wife) have children to ensure the family line.

By the power of Tonio's almost inhuman soprano voice, Guido is roused from his depression, and takes him as a star student. Tonio progresses in his lessons extremely quickly. Guido also has Tonio perform some of his original compositions, which begin to impress audiences at the conservatorio.

Tonio, for his part, struggles to come to terms with his castrato status; in his own mind, he is "less than a man". At first, he finds it difficult even to associate with his fellow castrati. As time goes on, he has a love affair with another castrato boy, Domenico, and after Domenico leaves, with Guido himself. He comes to dominate the conservatorio—in addition to being a star student, he soon befriends all the boys his age, and becomes something of a leader and confidant.

Tonio also continues his studies in fencing and firearms, which, in Guido's words, make him into a "hero" to his fellow students, especially after, in self-defense, he kills a student who vowed to kill him. As he was raised to be a gentleman, and because he was castrated relatively late in life, he continues to act like a man, unlike the more effeminate poses of castrati boys. Despite the fact he is a castrato, even local noblemen come to respect him both as a sparring partner and as a friend.

However, Guido and others need to scheme to get Tonio, finally, out of the conservatorio and onto the stage. After his debut, Guido and Tonio travel to Rome for his operatic premiere. There he gains the patronage of a powerful cardinal, Calvino, and befriends a powerful count from Florence, di Stefano. Although he is almost booed off the stage for upstaging the operatic star Bettichino, he proves a great success, and both he and Guido have bright futures in front of themselves. Tonio even becomes lovers with an English noblewoman and widow, Christina, seemingly restoring him to his former status.

Nonetheless, Tonio is unable to break free of the desire for revenge against Carlo. After having two children by Carlo, Tonio's mother, Marianna, dies. Soon afterwards—and before his Mardi Gras opera performance—hitmen sent by Carlo try to kill him. Against the wishes of all his friends, Tonio vows to return in time for an Easter opera, then disappears.