In 1904 an American naval officer, Pinkerton, rents a house on a hill overlooking the city of Nagasaki. He has procured the house for himself and his new Japanese fiancé, a 15-year-old girl known as Madame Butterfly. Because Japanese marriage laws are relatively lax, Pinkerton plans to marry his bride until he goes back to the United States to marry an American. In the process of the wedding, it becomes clear that Butterfly is much more invested in the wedding than Pinkerton, having converted to Christianity for her new husband. In the middle of the ceremony, Butterfly's uncle, a Buddhist priest, arrives and places a curse on Butterfly. The other guests, her family members, renounce her and leave. Pinkerton tells Butterfly that he will take care of her.
Pinkerton leaves for three years and Butterfly's maid, Suzuki, tries to convince her that he is never coming back, but Butterfly is convinced that he will return to her. The American consul, Sharpless, comes to see Butterfly, to read a letter to her from Pinkerton that says he is coming back to Japan, but that they are no longer married. Butterfly is so excited to hear from him that she does not let the Consul finish reading the letter, content to live in a delusion that she will soon be reunited with her love. Butterfly then reveals to Sharpless that she had a son with Pinkerton, but that Pinkerton does not know.
In the morning, when Butterfly is sleeping, Pinkerton arrives at the house with Sharpless and his new American wife, Kate. Kate has agreed to raise Butterfly's child as her own. Pinkerton cannot bring himself to break this news to Butterfly and leaves it to Kate and Sharpless to do so. When Butterfly awakens and learns the news, she says that she will hand over her son only if Pinkerton comes to her himself. She says goodbye to her son then ties a blindfold around his eyes so that he cannot see her kill herself. Devastated at losing both Pinkerton and her son, Butterfly commits ritual suicide with a knife of her father's. When Pinkerton rushes into the room he realizes that he is too late to save her, and Butterfly has died.
