Shen Te the prostitute has been rewarded for her goodness by the gods, who have bestowed a gift of a large sum of money upon her. With that money, she buys herself a tobacconist's shop. Somewhat ironically, given what we know about the appalling damage that tobacco does to health, this is considered a more respectable occupation than her previous one.
Before long, Shen Te's business has run into serious trouble. This is largely because the kind Shen Te, a woman who lacks a ruthless streak, is much too generous, giving out money left, right, and center to anyone with a sob story. It soon becomes patently obvious that Shen Te needs to do something fast if she's to keep hold of her business.
She does this by taking the unusual step of adopting the persona of Shui Ta, who's supposed to be her cousin. In her new persona, Shen Te is suddenly transformed from a kind, considerate woman to a ruthless, hard-nosed businessman determined to squeeze as much profit as possible out of the business.
Due to Shui Ta's much greater understanding of capitalism and how it works, he's able to expand the small business into a large factory, where men, women, and children workers are ruthlessly exploited. In turning into Shui Ta, Shen Te may have saved her business, but in the process, she's lost her soul.