Action, thriller, comedy, romance, mistery, high school bullying, everything in there but written with competency and beeing serious about bullying. The series is about golden bars hidden in the high school and the NIS agent (Seo Kang Joo) had to find them going undercover as a student. His teacher (Jin Ki Joo in a hilarious excelent performance) mistrust him and try to unmask him causing very funny consequences. There are three NIS agents who support Seo Kang Joo who make his mission not so easy. The villain in the series is the Principal (Kim Shin Rok who is become specialized in villain character) That is a very entertaining series and recomend it.