Lieutenant Pinkerton of the United States Navy has taken out a 999-year lease on a house in the hills above Nagasaki, where he intends to live with his bride-to-be, a geisha called Cio-Cio-San, or Madam Butterfly. The marriage-broker, Goro, shows him the house while wedding preparations get underway. Pinkerton revels in the elasticity of Japanese marriage contracts, under which the husband’s absence, even for so short a time as a month, constitutes a divorce. He laughs off the attempts of the American Consul, Sharpless, to warn him that Cio-Cio-San is taking the marriage seriously.
Cio-Cio-San arrives with a crowd of friends and relations and shows Pinkerton her few but treasured belongings. It emerges that she comes from a noble but poverty-stricken family and has had to earn her living as a geisha. Her father committed suicide on the orders of the emperor. The marriage ceremony takes place but the celebrations are interrupted by the arrival of Cio-Cio-San’s uncle, the Bonze, a Shinto priest, who denounces her for converting to Christianity. Her family and friends turn on her and reject her. Cio-Cio-San is left alone with Pinkerton. She assures him that he is all that matters and rejoices in her love for him.
Pinkerton has been gone for nearly three years and no word has been heard from him. Cio-Cio-San and her devoted servant Suzuki are still living in the house that he bought but have almost no money left. Scorning Suzuki’s doubts, Cio-Cio-San is convinced that Pinkerton will return and turns down the marriage offer of the wealthy Prince Yamadori. Sharpless has had a letter from Pinkerton, saying he is returning to visit Nagasaki, but does not want to see Butterfly. When she realises she has been abandoned, Butterfly shows Sharpless the child she has had by Pinkerton. As he leaves, Sharpless promises to let Pinkerton know. Suddenly the harbour cannon is heard, signalling the arrival of Pinkerton’s ship, the Abraham Lincoln. As night falls, Suzuki, the child and Butterfly settle down to wait.
Dawn breaks and Cio-Cio-San is still waiting. Suzuki persuades her to go and rest. Sharpless arrives with Pinkerton and his new American wife, Kate. They have now decided to adopt the child. Pinkerton, belatedly realizing the extent of Cio-Cio-San’s devotion, rushes away, unable to face her. Cio-Cio-San wakes to find a strange woman in her house and finally understands the truth. She agrees to give up her child on condition that Pinkerton comes in person to fetch him. Left alone, she takes a last farewell of her son and kills herself.