Act I The walls of the imperial palace. The square is full with a crowd which is listening to the Mandarin: Turandot, daughter of Altoum, the Emperor, will marry the prince who manages to solve three riddles. He who fails in this task will be beheaded, like the Prince of Persia, whose sentence is soon to be carried out. The eager crowd demands that the Prince be executed forthwith, in the resulting hubbub many fall to the ground, including Timur, deposed king of Tartary. A youth — Prince Calaf — runs up to assist Timur, whom he recognizes to be his father, but begs the latter to keep silent as he is fugitive. Timur tells his son of the great help given him by Liu, his slave girl, and how she had never left his side. When Calaf asks her why she had remained faithful to his father, she replies that it is because Calaf once smiled upon her. The executioner makes his appearance. All are eagerly awaiting the rising of the moon when the execution is due to take place, but the sight of the young Prince of Persia arouses the mob’s pity.
Calaf is ready to curse the Princess but his curse freezes on his lips when the Princess herself, shining with an imperious and almost unreal beauty, appears in the imperial box. Calaf makes for the gong ready now to challenge her to a battle of wits. The Princess’s three ministers — Ping, Pang and Pong — try to dissuade him, pointing to the head of the executed Prince of Persia. Liu implores Calaf to think of his old father. The Prince comforts her and asks her to look after his father, then he runs up to the gong and strikes it three times: to summon Turandot.
Act II Ping, Pang and Pong lament the fate of the dead princes and think longingly of their distant homes. They pray that the Princess may find her true love soon, for then life in China would improve. The square before the palace. The wise men hold scrolls in their hands which contain the answers to Turandot’s riddles. The Emperor seats himself on the throne. He tries to persuade Calaf to withdraw from the hopeless contest. Turandot too warns him of the consequences explaining why she has devised the contest: she is avenging the rape and murder of her ancestress, the Princess Lou-Ling. But Calaf refuses to desist. He gives a speedy answer to the first riddle — hope, nor does he have much trouble in finding the answer to the second riddle - blood. Annoyed, the Princess puts the third question and Calaf gives the right answer — Turandot. The vanquished Princess begs the Emperor not to hand her over like a slave to an unknown foreign man; Altoum replies that his oath is sacred. But Calaf does not wish for a wife who does not love him. He proposes to Turandot that if she should guess his name by dawn, he will die. The crowd acclaims the winner of the contest and wishes their Emperor long years of life.
Act III The city streets. Night-time. The voices of the heralds are heard: “No one shall sleep this night!” — until the name of the stranger is discovered. Calaf is confident that he will win the Princess’s love. Ping, Pang and Pong try to bribe Calaf to tell them his name, offering him women, riches and power, but the latter refuses to be moved! The crowd begs him and then threatens him but, at this very moment, guards bring in Timur and Liu whom they have seen in the square together with Calaf. Liu admits that she knows Calaf’s name, but she will not reveal it: her love gives her the strength to remain silent. As the executioner approaches, she snatches a dagger and kills herself. Before dying, she predicts that Turandot too will fall for the Prince. Timur is overcome with grief and rage. Frightened by his curses, the crowd intones prayers of atonement. Liu’s body is carried away, followed by the funeral procession. Calaf and Turandot are left alone. A passionate kiss from Calaf transforms the Princess into a human being. As dawn breaks, Calaf reveals his name to Turandot but, to the gathering crowd and to her father, she presents him in a different way: “His name is Love!”