Homicide detective Jung Jae-gon (Kim Nam-gil) is chasing after a suspect of a murder case (Park Sung-woong). He knew his suspect would get in touch with his lover Kim Hye-kyung (Jeon Do-yeon), a madam at a third-rate bar. Jung goes undercover as the suspect's former cellmate and becomes the floor manager at the bar where Kim works, and watches her every move. But as Jung spends more time with her, he feels a strange sense of guilt and his resolve to catch the suspect is shaken. Having dedicated his life to police work, Jung doesn't understand the feeling he feels towards Kim. On the other hand, Kim waits tirelessly for her lover to come back to her, but she begins to open up to Jung, who is always by her side.