Rubuta ci gaba ga wannan sakin layi - A watan Afrilu 1975 a "Dreamland", Saigon mashaya da gidan karuwai, jim kaɗan kafin ƙarshen Yaƙin Vietnam
, ita ce ranar farko ta Kim a matsayin bargirl. Yarinyar mai shekaru goma sha bakwai mai shekaru goma sha bakwai ya jawo shi ta hanyar Injiniya, wani dan wasan Faransa-Vietnam wanda ya mallaki gidan. A bayan fage, 'yan matan sun shirya kansu don wasan kwaikwayon na dare, suna ba'a game da rashin ƙwarewar Kim ("Overture / Backstage Dreamland"). Sojojin ruwan Amurka, sun san cewa ba da daɗewa ba za su bar Vietnam, suna yin biki tare da ma'aikatan jima'i na Vietnamese ("The Heat Is on in Saigon"). Chris Scott, wani jami'in da ya yi farin ciki da yanayin kulob din, abokinsa John Thomas ya karfafa shi ya tafi tare da yarinya. 'Yan matan suna fafatawa don samun lakabin "Miss Saigon", kuma wanda ya yi nasara ya zama dan Marine. Chris ya yi mamakin yadda Kim ba ta da wayo. Gigi Van Tranh ta lashe kambin wannan maraice kuma ta roki sojan ruwan da ya ci caca ya dauke ta zuwa Amurka, yana bata masa rai. 'Yan matan wasan kwaikwayon suna yin tunani game da burinsu na rayuwa mafi kyau ("Fim a cikin Zuciyata"). John ya sayi ɗaki ga Chris da budurwa Kim ("Ma'amala"). Kim yana da jinkiri da jin kunya, amma tana rawa da Chris. Chris ya yi ƙoƙari ya biya ta ta bar gidan wasan dare. Lokacin da Injiniyan ya tsoma baki, yana tunanin cewa Chris ba ya son Kim, Chris ya bar kansa a kai shi ɗakinta ("The Dance").