California, 1870s. The cowboy Lincoln 'Linc' Bartlett finds out there's a slave auction of Chinese women in San Francisco and he intervenes and purchases the Chinese Kim Sung from the auction with the intent of setting her free. But it doesn't occur to Linc that setting her free isn't enough. Where is she going to go? Kim doesn't speak English and she's just going to be exploited by somebody else. Linc takes Kim home to serve as a housekeeper. Ma Bartlett Linc's mother, is not happy that a Chinese girl is living in her home, and even less happy when Kim and her son fall in love. Their affair also arouses the jealousy of Cheng Lu, a Chinese immigrant.