Queen of Revenge: Sister's Fury

Lisa fights in underground bouts and the money keeps her and her younger sister Annie fed. Annie has an intellectual disability and the two have depended on each other since childhood. Lisa beats up a hooligan who harasses Annie and gets a year in prison for it, and before she goes she leaves Annie with her boyfriend Robert. She comes out to find Robert has been seeing someone else and Annie is gone. Robert had debts, and he sold Annie to a gang boss to cover them. Lisa goes looking. In the course of it she pulls another girl out of trouble, a woman also called Annie who is the boss's mistress, and this second Annie starts feeding her information about where the gang keeps people. She is found out and killed for it. Lisa dresses herself up as a dominatrix to get close to the boss, and she gets close enough to find her sister, who is being kept on drugs and used as leverage against her.