Seungri High School ranks as one of the worst of the 178 high schools in Seoul based on academic scores. Kang Se Chan is the top Korean language teacher who owns a famous teaching institute in Gangnam. Meanwhile, Jung In Jae is a short-term Korean language teacher at Seungri High who gets appointed as the homeroom teacher of class 2, the bottom of grade 2. When Se Chan transfers to Seungri Highto teach Korean language, he becomes the co-homeroom teacher of class 2-2. Both teachers run into many difficulties having to face bullies, academic underachievers, their parents and other teachers, as well as due to their different teaching methods. However, they need to put their differences aside in order to help their class successfully advance to their senior year.