Miss Saigon is a sung-through stage musical by Claude-Michel Schönberg and Alain Boublil, with lyrics by Boublil and Richard Maltby Jr. It is based on Giacomo Puccini's 1904 opera Madama Butterfly, and similarly tells the tragic tale of a doomed romance involving an Asian woman abandoned by her American lover. The setting of the plot is relocated to 1970s Saigon during the Vietnam War, and Madama Butterfly's story of marriage between an American lieutenant and a geisha is replaced by a romance between a United States Marine and a seventeen-year-old South Vietnamese bargirl.
https://en.wikipedia.org/wiki/Miss_Saigon