Act I
An officer in the American navy, B.F. Pinkerton, has fallen in love with Cio-Cio-San during his visit to Japan. Their wedding is about to take place in the house which Pinkerton has rented through the marriage contractor, Goro. Amongst the guests are Butterfly’s mother and relatives, her maid Suzuki and the American consul Sharpless. Sharpless asks Pinkerton to treat his young bride gently and take her love seriously. Pinkerton takes his warnings lightly: when two people fall in love, they cannot concern themselves with the future. Cio-Cio-San, whose name means Butterfly in Japanese, shows the contents of her suitcase to Pinkerton: statuettes of her ancestors, and a knife. When Pinkerton asks about the knife, Goro tells him that Butterfly’s father used it to commit harakiri. Since he passed away, Butterfly has earned her living as a geisha. Butterfly’s uncle, who is a Bonze – a Buddhist priest – enters, cursing Butterfly for abandoning her ancestry and her religion. The Bonze commands all of Butterfly’s relatives to leave the party and casts her out forever. Butterfly is crushed, and hopes that Pinkerton loves her enough to stay with her. Butterfly and Pinkerton seek comfort in each others’ embrace. However, their wedding night is overshadowed by the Bonze’s curse.
Act II
Butterfly waits in the ruined house, where Pinkerton abandoned her three years ago. Money is running short and Suzuki voices her doubt that Pinkerton will ever come back. Butterfly conjures up the memory of his promise to return as soon as the robin builds his nest. Sharpless pays a visit. Pinkerton is on his way, but Sharpless hesitates to tell Butterfly the truth – that Pinkerton has married an American woman. Goro attempts to convince her to marry prince Yamadori, who has courted Butterfly for a long time without success. When Sharpless makes her understand that Pinkerton will not come back to her, Butterfly presents her child by Pinkerton to Sharpless. She begs him to let her lover know about the child: he was born after Pinkerton’s departure. Pinkerton’s ship appears in the harbour. Butterfly is in a rush to prepare for his arrival, and Suzuki helps her decorate the house with cherry blossoms. They wait up all night for him.
Act III
When the sun rises, Butterfly and her child fall asleep. Both are weary from the nightwatch. Sharpless arrives with Pinkerton and Pinkerton’s wife Kate. They have come to pick up the child to give it a better future. When Suzuki tells Pinkerton about Butterfly’s patience and loyalty, Pinkerton asks Sharpless to bring him the child and pay Butterfly off. He is unable to face her again. Butterfly enters looking for Pinkerton, and is confronted with his wife. Sharpless informs her that Pinkerton and Kate have come to take her child away. Butterfly decides to obey Pinkerton’s wish and surrender the child. When Butterly is left alone she pulls out the knife which was the instrument of her father’s suicide, and takes her life. Pinkerton rushes into the house while calling out her name.