Lee Tang, who was discharged from the army six months ago, struggles with his life and dreams of visiting Canada. He works at a convenience store and relies heavily on his parents for support. One night, he is assaulted by a customer, leading to a violent confrontation and the subsequent murder of the customer. Tang is guilt-ridden and prepares to turn himself in but discovers his victim was a serial killer. Dutiful detective Jang Nan-gam remains uncooperative and keeps investigating. It is unclear if Nan-gam is onto him, but Tang continues to kill, revealing his hidden talent for detecting and killing previously unpunished evildoers without leaving any traceable evidence. The story explores the question of whether Tang is serving justice or evading it.