Kyungsoo is a filial son who enjoys his leisure time writing letters to the people who are special to him. Fate will bring him to the university's notorious bad boy, Kai who has a cryptic hate towards the lovable Kyungsoo.  Chanyeol, the mysterious popular guy, has a secret he doesn't want anyone to know. Baekhyun who has an unutterable attraction towards Chanyeol will do everything to know that secret.