Vigilante tells the story of the journey of a young man bent on seeking revenge after witnessing his mother's brutal murder as a child. Since the traumatic event, Kim Ji Yong has dedicated himself to martial arts, becoming an exemplary student at the police academy. Upon his mother's attacker's release, Ji Yong catches him in the midst of another assault, setting him on a path of taking justice into his own hands, garnering unwelcome attention from the media and police.  Refusing to give up his mission, Jiyong finds himself assuming the role of a vigilante, correcting the wrongs of repeat offenders.