Act I

American naval officer Benjamin Franklin Pinkerton is renting a beautiful house on a hill in Nagasaki, where he plans to live with his newlywed Japanese wife until he leaves Japan and finds a suitable American bride. Japan’s marriage laws are very convenient for Pinkerton, especially since they hold no authority beyond Japanese borders. This means he can live with the 15-year-old Chōchō-san (Butterfly in Japanese) as long as he pleases, considering her his wife. In his Western manner, Pinkerton affectionately calls his young bride “Butterfly.” The girl is so enchanted by her marriage to the American gentleman that she is willing to give up both her relatives and her religion. The joy of the wedding celebration is abruptly interrupted by Butterfly’s uncle, a Buddhist monk, who curses the bride for renouncing her faith. Following this, her relatives also turn their backs on young woman. Nevertheless, Pinkerton and Butterfly joyfully prepare for their wedding night.

Act II

Three years later, Butterfly is still waiting in vain for her husband, who departed shortly after their wedding. Her maid, Suzuki, realises that Pinkerton will not return, but she cannot convince her mistress. The matchmaker Goro - who arranged the couple’s marriage three years ago - now brings a new suitor, the wealthy Prince Yamadori, but Butterfly dismisses them both. Soon after, Consul Sharpless arrives with a letter from Pinkerton, asking the consul to inform Butterfly that he does not intend to return. Sharpless tries to gently prepare her and asks what she would do if Pinkerton never came back. The very idea seems impossible to Butterfly. She then asks the consul to tell her husband that soon after his departure, she gave birth to their son, who is now three years old. Sharpless cannot bring himself to tell her the truth and leaves. From the hill, a ship entering the harbour comes into view - it is Pinkerton’s ship arriving in the harbour. Butterfly orders Suzuki to fill the house with flowers. Then, she sits and waits with her child, expecting her husband’s arrival. Hours pass. Suzuki and the child eventually fall asleep, while Butterfly remains motionless, waiting.

Act III

Dawn breaks. Suzuki wakes and urges Butterfly to get some rest. Meanwhile, Sharpless, Pinkerton, and his American wife, Kate, approach the house. Kate is ready to raise Butterfly’s child as her own. The three enter the flower-filled home. Pinkerton realises how deeply Butterfly had waited for him, how boundless her love was, and how grave his mistake had been - he cannot bring himself to face her. Only Suzuki, Sharpless, and Kate remain. They try to persuade Butterfly that for the sake of the child’s future, it is best for him to grow up in America. Butterfly agrees, on one condition: Pinkerton must come to see her in person. Then, she prays before her ancestral gods, bids farewell to her son, and disappears behind a screen - where she takes her own life with the seppuku dagger, a keepsake from her parents that she had brought with her to this house when she was full of joy and hope.