An unnamed devoted mother sells herself by night on the streets of Shanghai in order to support herself and her infant son. When a gambler who calls himself "the Boss" strong-arms his way into becoming her pimp, she flees with her son and attempts to earn an honest living, but the Boss tracks her down and forces her back into prostitution. When her son reaches school age, she begins hiding away enough money to pay his tuition. Although her son is ostracized by other kids due to her profession, she takes great joy in providing an education and a potential better future for him. When the other parents want the boy expelled, a kindly principal fights to keep him in school. Meanwhile, the Boss finds her hidden cash, adding financial woes to the problems of social injustice.