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 fulfil. "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 ...