In 1919, on a steamy South Pacific Island, an unlikely party of travelers are stranded due to a cholera quarantine. They are a missionary couple, the Davidsons, a Doctor McPhail and his wife and Sadie Thompson, a free-spirited prostitute fleeing a conviction. She runs afoul of Davidson, a sin-hating missionary who decides to save her soul. Fleeing the police in Honolulu and a prison term in San Francisco, Sadie eventually sees in Davidson the promise of a better life and accepts his teachings, although becoming uncertain and dispirited. Davidson conceives a passion for her as his "Mary Magdalene" and, the night before her deportation, acts on this. In shame and confusion, he commits suicide. Sadie, unaware of his suicide, emerges the next morning as her former spirited self, declaring that all men are "pigs."