A quiet, professional killer, Hyun-jun, arrives at a house to kill a man in his sleep, only to discover a woman alone under the sheets. She shouts at the dazed Hyun-jun, "What's the matter with you. I paid for you, so just kill me." Jin-young has decided to kill herself after a traumatic break up with her lover of seven years, but she wants to go out with a bang, not with a miserable and lonely dose of commonplace sleeping pills. Hyun-jun is furious at the woman and abandons the mission despite the fact that he has a contract to fulfill. "You should kill yourself; I'm not your suicide assistant." This is how Hyun-jun and Jin-young first meet. The most extraordinary love story begins.