Whakakiia te rerenga e whai ake nei: I te Paenga-whāwhā 1975, i "Dreamland", he pae me te whare moepuku o Saigon, i mua tonu o te
I te mutunga o te Pakanga o Vietnam, ko te rā tuatahi a Kim hei kotiro kai. Ko te kotiro whenua tekau ma whitu-tau te pakeke e toia ana e te Engineer, he tangata tinihanga French-Vietnamese nona te waahi. I muri i te paparanga, kei te whakareri nga kotiro mo te whakaaturanga o te po, e tawai ana ki te koretake o Kim ("Overture / Backstage Dreamland"). Ko nga Marines o Amerika, e mohio ana ka wehe wawe atu ratou i Vietnam, he huihuinga me nga kaimahi moepuku Vietnamese ("The Heat Is on in Saigon"). Ko Chris Scott, he kaitiaki kua ngaro i te tirohanga o te karapu, ka akiakihia e tana hoa a John Thomas kia haere me tetahi kotiro. Ka whakataetae ngā kōtiro mō te taitara o "Miss Saigon", ā, ka tohaina te toa ki tētahi Marine. E pā ana a Chris ki te kore tinihanga o Kim. Ka riro i a Gigi Van Tranh te karauna mo te ahiahi nei, ā, ka inoi ki te hoia moana i toa i te rota kia whakahokia ia ki Amerika, e whakaoho ana i a ia. Ka whakaaroaro nga wahine whakaari ki o raatau moemoea mo te oranga pai ake ("Movie in My Mind"). Ka hokona e John he ruuma mo Chris me te wahine wahine a Kim ("Te Whakawhitinga"). He pōhēhē a Kim, he whakama hoki, engari e kanikani ana ia ki a Chris. Ka ngana a Chris ki te utu i a ia kia wehe atu i te karapu pō. I te wa e uru ana te Engineer, i te whakaaro kaore a Chris e pai ki a Kim, ka whakaae a Chris kia arahina ia ki tona ruuma ("Te Kanikani").