Kim Sun-woo (Lee Byung-hun) is a high-ranking enforcer and loyal subordinate of crime boss Kang (Kim Yeong-cheol). The two share concerns over business tensions with Baek Dae-sik (Hwang Jung-min), a son from a rival family. Previously Sun-woo had beaten up Baek’s men for overstaying their welcome at their nightclub. Kang, preparing to leave on a business trip, assigns Sun-woo to shadow his young mistress Hee-soo (Shin Min-ah), whom he fears is having an “affair” with another man.A Bittersweet Life 2005
As Sun-woo performs his duty — following Hee-soo, and escorting her to a music recital – he becomes quietly enthralled by the girl’s beauty as glimpses into his lonely, empty personal life become prevalent. When he does come to discover Hee-soo and her lover at her home, he beats up the man and prepares to inform Kang. However, he changes his mind and spares the two on the condition that they no longer see each other again, earning him Hee-soo’s enmity.
Later, a man asks Sun-woo to apologize for beating up Baek’s men, but he refuses. Agitated, he gets drunk in his apartment, and is kidnapped by Baek’s henchmen. They prepare to kill him, but Kang saves him with a phone call. Kang, who has learned of his attempted cover-up of Hee-soo’s affair, questions his motive, but he doesn’t answer. Kang orders his men to torture Sun-woo, but gives him a chance to fix his mistake. Instead, Sun-woo escapes and vows revenge.
Sun-woo delivers Hee-soo a farewell gift, then attempts to buy a handgun. The deal goes bad and he ends up killing the arms dealers. This incurs a vendetta with the brother of one of the dealers, who goes to the nightclub he works at. Sun-woo lures Baek to an ice rink and kills him, getting injured in the process.
