Build a movie plot around this: Why does Sun-woo beat up several henchmen? overstaying their welcome
Kim Sun-woo (Lee Byung-hun) is a high ranking mobster and enforcer for Kang (Kim Yeong-cheol), a cold and calculating crime boss to whom he is unquestionably loyal. The two share concerns over business tensions with Baek Dae-sik (Hwang Jung-min), a son from a rival family, which is when Kang assigns Sun-woo what is perceived to be a simple errand while he is away on a business trip to shadow his young mistress, Hee-soo (Shin Min-ah), whom he fears is having an "affair" with another man, giving Sun-woo the mandate to kill her (and her paramour) if he manages to discover it. As he performs his duty following Hee-soo, and escorting her to a music recital one day he becomes quietly enthralled by the girl's beauty and innocence as glimpses into his lonely, empty personal life become more prevalent. When he does come to discover Hee-soo's lover directly in her home, he fiercely beats him and prepares to inform Kang, but his attraction to her causes him to hesitate. He thus spares the two on the condition that they no longer see each other again, earning him Hee-soo's enmity.Meanwhile, Sun-woo continues to be embroiled in personal business with Baek Dae-sik over having beaten up several of his henchmen earlier for overstaying their welcome at the hotel. He is then threatened by one of his enforcers to apologize, but he adamantly refuses, fueled by his frustrations over Hee-soo. As he relaxes in his apartment later one night, he is suddenly kidnapped by Baek's men to be tortured, but before they can do so they receive new orders via phone call and he is abruptly carried off to Kang, who has returned from overseas and has found out about his attempted cover-up of Hee-soo's affair. Kang's men torture him into confessing why he lied until he is left alone to think about his answer. A daring but messy escape follows, after which Sun-woo plans his revenge.Help from one of Sun-woo's loyal men provides him with money and new clothes to go about his plan: he secretly delivers Hee-soo a gift to make amends and...