In front of the walls of the imperial palace in Beijing, a mandarin reads a proclamation announcing that the princess Turandot will marry only a suitor of royal blood who will answer the three riddles set by her. Suitors who will fail to answer will be beheaded as many others before. The prince of Persia has just failed in his attempt and will soon find his death at the gallows. The crowd awaits the execution eagerly while the others call the princess to stop the cruel bloodshed. During the commotion an old man falls to the ground. A younger man rushes to his aid, recognizing that the old man is his father whom he thought dead. The happy reunion between father and son is somewhat quieted as Calaf, the young man, informs his father, Timur the old king of the Tartars, that they are persecuted by enemies. Timur has escaped the enemy with the aid of Liu, his faithful servant. As the prince of Persia is led to the scaffold, the crowd laments his beauty and his young age and asks to keep him alive. Turandot appears for an instant signaling that the execution can proceed. Calaf, catching her sight for a mere instant, is smitten. He wants to answer the riddles in order to marry the princess. Timur entreats his son to run away and save his life, and the three imperial ministers, Ping, Pang and Pong also beg the anonymous man to reconsider. Even Liu, who has secretly loved Calaf for many years, asks him to leave but he consoles her, saying he can not be moved. Calaf has made up his mind. He approaches the palace gates, strikes the gong thrice and calls three times the name of Turandot accepting the challenge that many before him failed and paid for their failure with their own life.
The three ministers, Ping, Pang and Pong, discuss the funeral rites or the victory parade for the unknown prince. They lament Turandot’s ongoing bloodshed and long for the good old days of the quiet past, hoping they will be able to enjoy the joys of nature. They day dream about a different era, a quiet time that will arrive once one suitor answers the riddles and conquers the ice princess. But soon enough they are brought back to reality and proceed to the royal palace to attend, yet again, one more riddle ceremony.
Many have gathered at the palace where even the old emperor Altum implores Calaf once more to save his life. But no one can change Calaf’s mind. Turandot appears and explains why she is so cruel to her suitors. A long time ago, she says, a foreign king has ravished her ancestress and Turandot has vowed to avenge the horrible deed. Calaf is ready and provides the answer for the first riddle with ease. It is hope which is born anew every night. The second riddle is tougher for Calaf but again he provides the right answer: blood kindles like a flame. Turandot is somewhat agitated. Her third question seems to beat the prince: “Which ice gives fire?” she asks and eventually Calaf does claim his victory. The answer of course is Turandot herself. The people hail the victorious prince but Turandot begs her father: she does not want to marry the prince. Altum cannot help his daughter, but Calaf has a proposal: he will ask the princess one riddle. If she can guess his name by dawn he will be ready to die. Turandot accepts the challenge.
Turandot sends her messengers through the city to find out the prince’s name. No one shall sleep tonight, comes the decree, until the name is found out. In the palace garden Calaf awaits morning. The three mandarins ask him to run away and offer him money and other women. But Calaf will not give up Turandot. Torturers drag in Timur and Liu. They have been seen speaking with the prince and it is hoped that they can provide the name all Beijing is searching for. Turandot commands them to speak, but Liu in order to save her master’s life, says that only she knows the name but will never disclose it because of her love to Calaf. Snatching a dagger from one of the guards, Liu stabs herself and dies. Calaf and Turandot remain alone on stage. He tears the veil off her face and kisses her passionately. The kiss melts in the ice princess. She confesses that from the beginning she has feared and loved the unknown prince. She hopes Calaf is happy to know she loves him and begs him to leave. But Calaf simply reveals his true identity to Turandot putting his life in her hands and gives her a proof of love. She again assumes her former attitude, rushing to summon the Emperor and the people, announcing that she has revealed the stranger’s name so she can kill him. When the emperor and the crowed are bothered, she finally speaks out the unknown prince's name: “Amore”.