The story focuses on the conflicts between the young teachers and the problems that high school students have. Jang Yi San is a timid and incompetent homeroom teacher who has to teach the only daughter of a highly dangerous mob leader, Eun Byul. Eun Byul is a new student at MyungMoon High with little drive to succeed.—wiki

There are some offers that you just can't refuse. Jang Yi San (Yang Dong Geun) is a rookie teacher who is put in charge of a homeroom full of misfits and troublemakers, including Chae Moo Shin (T.O.P) and Yoo Eun Byul (Park Min Young). Eun Byul happens to be the daughter of Yoo Jae Gon (Park Joon Gyu), the head of a dangerous gangster organization. When Jae Gon realizes that Yi San can make his only daughter actually interested in studying, he makes the teacher an offer that he can't refuse: become Eun Byul's private tutor in exchange for one million won.