He perceives innocence in her that all of the other girls dont have. Although a different girl is crowned Miss Saigon, John sees that his friend liked Kim, and so he buys a room from the engineer for Chris and Kim. After some reluctance, they both enter the room. After spending a night together, Chris realizes that he has fallen in love with Kim. It is apparent that she has fallen in love with him too because when he tries to give her money, she refuses it. They both promise their love to each other and Chris tells her that he will take care of her. Chris takes some time off to spend with Kim. They get married, but during the wedding Thuy who is Kims cousin comes in and is very angry because he was engaged since they were thirteen. She lets him know that she does not have any feelings for him and that their arranged marriage no longer exists because her parents are dead. Chris then promises Kim to take her with him when he leaves to return to America. Three years later there is a street parade in Ho Chi Ming City which used to be Saigon. Thuy tells his soldiers to find Kim. She has been hiding in a poor area waiting for Chris to come back.
The audience then sees Chris in America with his new wife Ellen. Both Ellen and Kim are very much in love with Chris. Thuy has ordered the Engineer to find Kim, and he brings her to him. He proposes to marry her again, but she refuses. She shows Tam, Chriss son to him, and Thuy becomes very angry. He is about to kill Tam with a knife but Kim kills him and runs away with Tum. She runs to the Engineer and tells him what she did, he is very unhelpful until he realizes that Tum is Chriss son. The Engineers main mission during the whole play is to get a passport to the United States. He sees Tum as his perfect chance. Thus, he agrees to help Kim and the boy. In the second part of Miss Saigon, the audience is reintroduced to John who is now working with an organization that reconnects children made during the war to their American fathers. John informs Chris that Kim is still alive and this relieves him. John also lets Chris know that he has a little boy and that he should go to Bangkok with Ellen.
Because of this, Chris tells Ellen about Tam and Kim. Once again, the Engineer has a shady club in which Kim dances. This is where John finds her and tells her that Chris is back. He attempts to tell her that Chris is married, but Kim is too happy to listen to him and tells her small boy that his father is back. She truly believes that Chris will take them back to America with him. John cant bear to tell her the truth and instead swears to bring Chris back. The Engineer doubts Chris will come and tells Kim to go find him herself. Thuys ghost appears to Kim and he tells her that Chris will betray her as she was betrayed on the night of the fall of Saigon. With this, Kim has a flashback to what actually happened last night. Chris was called to the embassy, and after telling her to pack and leaving his gun with her, he leaves. After entering the embassy the gates are closed and there is a call from Washington for the instant evacuation of the Americans that remained.
No more Vietnamese are allowed into the gates. Chris tries very hard to leave the embassy to look for Kim, but John ultimately punches him and he is put into the last helicopter leaving. Kim promises to wait for him. After the flashback, the audience sees Kim excitedly dressed in her wedding clothes and she goes to where Chris is staying. She finds Ellen and thinks it is Johns wife, but Ellen tells her she is Chriss wife. Kim, however, does not believe her. She pleads with Ellen to take her boy so that he wont grow up in the streets. Ellen does not agree, and tells her that they will help him, but that she wants her own children with Chris. Devastated, Kim runs out of the room. Afterwards, John and Chris arrive to find Ellen and she tells them that Kim has visited and knows everything. Chris and John feel terrible that they werent able to break it less painfully to her.
Ellen makes Chris choose her or Kim, and he reassures her that what they have was much stronger than what he had with Kim. He decides to support his son and estranged wife by sending them money from America, but not actually taking them with him. John cautions that Kim will not let them leave without Tam. They leave to tell Kim what they have decided. Back in her room, the audience sees Kim speaking to Tam. She tells him he has a father now and should be really happy. In her room, Kim tells Tam that he should be happy because he now has a father. She tells him that she cannot go with him but will be watching over him (The Sacred Bird/Little God Of My Heart/This Is The Hour (reprise)).
Chris, Ellen, John, and the Engineer arrive just outside her room. The Engineer comes in to take Tam outside to introduce Tam to his father. While this is happening, Kim steps behind a curtain and shoots herself. As she falls to the floor, everyone rushes into the room at the sound of the gunshot and find Kim mortally wounded. Chris holds Kim in his arms and asks what she has done and why she did this, as she explains that the gods have guided him to his son. Chris begs her not to die, as she asks him to hold her one last time. After sharing one final kiss, Kim says her final words to Chris, echoing what he said to her from the song Sun and Moon (How in one night have we come so far?) and she dies in his arms (Finale).