Honed from childhood into a merciless killing machine by a criminal organization, assassin Sook-hee is recruited with the promise of freedom after ten years of service. However, secrets from her past destroy everything she’s worked for and now she embarks on a roaring rampage of revenge.
Chinese secret agent Da-hee receives intel that a large number of illegal firearms are being smuggled into Korea and is sent to investigate the case. She meets Su-han, who is supposed to help her with the case, but due to his lackluster skills they fight over trivial things. But as their witnesses are suddenly murdered, the two of them quickly become the prime suspects.
Shin-ah, a free spirit, has an unexpected encounter with Dong-gi, who seeks excitement. After a passionate night, she breaks up with her boyfriend and reunites with Dong-gi when he calls. The two fall madly in love.