In nineteenth-century Italy, promising singer Rosi Belloni meets American music student Harry Peters and the two become engaged and she falls pregnant by him. Before she can tell him this news, he informs her he is returning to the United States for three years for further musical education. Unwilling to stand in the way of his future, she does not tell him about her pregnancy. Although he promises to be in contact within a year, she receives no word from him.
Five years later Peters, now a conductor at the Metropolitan Opera in New York City, returns to Italy with his new American wife. In the meantime Rosi Belloni has risen to become a leading opera singer, and is chosen by Puccini to sing the title role in his new opera Madame Butterfly at La Scala. Encountering the five-year-old son who has been raised to honour the idea of his father, Peters comes to realise what he missed by not marrying Belloni. In turn she comes to appreciate how much her own life resembles that of Madame Butterfly.
