The action takes place in Nagasaki (Japan) in the late nineteenth century. US Navy Lieutenant Pinkerton decides to marry a young Japanese geisha Chio-Chio-san, nicknamed Butterfly. Goro, a professional Japanese matchmaker, shows him a house rented for the future couple. American Consul Sharples, a friend of Pinkerton, arrives for the ceremony. During their conversation, the groom’s cynical intentions become clear: in America, his union with the Japanese woman will have no legal force, so he will be able to consider himself free from this marriage. Sharples is alarmed by such a cynical attitude and warns Pinkerton that Chio-Chio-san is too young, pure and sincere. Pinkerton does not hear arguments and even offers a toast for the day when he really gets married in his homeland. The voices of Chio-Chio-san and her friends are heard. The girl tells her lover about her life: her father was a noble samurai, but poverty forced the girl to become a geisha. She is ready to accept Christianity for his sake and break off relations with her family. The marriage ceremony begins, which is attended by the Imperial Commissioner. She is interrupted by the angry voice of a bonzo, Uncle Chio-Chio-san, who curses his niece for renouncing her faith. Abandoned by loved ones, the girl cries. Pinkerton soothes her anxiously.
Three years have passed. Chio-Chio-san is waiting for Pinkerton, who went to America after the wedding. Abandoned by her husband and relatives, she lives in her house with a maid and a young son, whose existence Pinkerton still does not know. Suzuki prays to the gods to relieve the woman of deprivation and mental suffering. She warns Butterfly that foreign men hardly return to their Japanese wives. But Chio-Chio-san passionately defends his love and assures that Pinkerton will return. Sharples arrives, who, at Pinkerton’s request, is to prepare Chio-Chio-san for the news: he has married an American woman. Their conversation is interrupted by Goro, who persistently woo Chio-Chio-san to the rich Prince Yamadori. Without thinking, Butterfly refuses him. The consul tries to read Pinkerton’s letter to Chio-Chio-san, but when she hears that the man is alive and well and is coming to Nagasaki soon, she does not allow him to finish reading. In response, Sharples advises the woman to accept Yamadori’s offer and hints that her husband may not return. However, the young woman’s faith is unshakable. She informs the consul that she has a son, and Pinkerton, learning of him, will return immediately. Sharples promises to tell a friend. A cannon shot is heard – an American ship enters the port, on which Pinkerton is to arrive. In joyful anticipation, Chio-Chio-san and the maid decorate the house with flowers.
Yesternight. Chio-Chio-san’s expectations for the meeting are in vain. Tired, she lulls the child and falls asleep. Pinkerton appears with his new wife Kate and the consul. Sharples reveals the truth to Suzuki and asks to persuade Butterfly to give the child to his father. Learning from Suzuki how Butterfly was waiting for her husband, decorating the house with flowers, excited and confused Pinkerton leaves the house. Seeing Kate and the consul, Chio-chio-san begins to realize everything. Sharples advises the woman to give the boy away. Butterfly asks that Pinkerton himself come for his son. When everyone leaves, the unhappy woman prepares for death. Unable to survive the betrayal, she gently says goodbye to her son and kills herself.
Libretto by Luigi Illica and Giuseppe Giacosa. Based on the play by David Belasco and the short story "Madame Butterfly" by John Luther Long.