No Mercy centers on In-ae, once a bodyguard and previously incarcerated, as she undertakes a violent quest to free her sister, Eun-hye, who has a developmental disability, from mistreatment, exploitation, and political wrongdoing. The film delves into troubling societal problems such as harassment, sexual assault, and the misuse of authority while revealing the disturbing reasons behind Eun-hye’s hardship. While the narrative does have some moments that don't quite add up and the action isn’t always impressive, the solid acting—particularly Park Se-wan's contribution—helps make this action-thriller an intense and affecting experience.

Source on TMDB