This final act is a short epilogue. It has the scene heading: MING-CHEN WU.
Willis sees his dad, Ming-Chen, and his daughter, Phoebe, in the kitchen. Ming-Chen is wearing an old shirt from the seventies, and he's in his eighties.
Willis remarks that Ming-Chen must've seen the Golden Palace reconfigured and redecorated hundreds of times. Willis also remarks that, while the scenery must've been dismantled and rebuilt so many times, it was all in service of a story that never changed and never truly existed. Chinatown was an illusion and also a prison.
But Phoebe can move freely between worlds, and Willis has hope that she can teach him and his father how to do the same thing.
Ming-Chen takes the stage and prepares to sing karaoke. He is going to sing a song about his home.
This chapter bridges the three generations of Willis's family. Ming-Chen, Willis, and Phoebe are all on a continuum of immigration from Taiwan to America. Willis finds himself somewhere in-between, while Ming-Chen's heart is still in Taiwan, and Phoebe's is someplace new.
Ming-Chen's decision to sing karaoke mirrors an earlier mention of karaoke in Act 2, when Ming-Chen sings John Denver. Willis remarks that it makes sense for a man from Taiwan, who has spent two thirds of his life in a foreign country, to "nail a song, note perfect, about wanting to go home."