A veteran detective who is about to retire unfolds a breathtaking psychological warfare with a mysterious man who follows his path while hiding his identity.

Na-mi and Sun-woo, the outcasts in school, plan to commit suicide instead of going to the school trip. On the moment of success, they find out that the girl, Chae-lin, who made their lives miserable is living a new happy life in Seoul. So, they decide to make revenge before ending their lives. However, when they finally spot Chae-lin, they see a good-hearted girl in front of them which makes their plans go awry.