Build a movie plot around this: Who has to shadow Hee-soo while Kang is away on business? Sun-woo
The answer to this question is:
Kim Sun-woo (Lee Byung-hun) is an enforcer and manager for a hotel owned by a cold, calculating crime boss, Kang (Kim Yeong-cheol), to whom he is unquestionably loyal. The two share concerns over business tensions with Baek Jr., a son from a rival family, which is when Kang assigns Sun-Woo what is perceived (at first) to be a simple errand while he is away on a business trip to shadow his young mistress, Heesoo (Shin Min-a), for fear that she may be cheating on him with another, much younger man, with the mandate that he must kill them both if he discovers their affair. As he performs his duty following Heesoo, 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 Heesoo's secret lover directly in her home, he fiercely beats him, but seeing the girl's traumatized state causes him to take pause, pulled by his attraction to her. He thus spares the two on the condition that they no longer see each other again, causing her to harbour enmity towards him, despite the fact he had saved their lives at his own expense.Meanwhile, Sun-woo continues to be embroiled in personal business with Baek Jr., 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 Heesoo. 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 Heesoo'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 co-workers provides him with money and...