Jonghyeon is known as a model student at school and at home. Meanwhile Ahn Haram, also in the same class, is a troublemaker who loves to play tricks. He is always under the watch of his teacher, and is often scolded. Jonghyeon plans to become a troublemaker like Ahn Haram so that his mom, a housewife who suffers from depression, would get out of the house. But it's not easy! He tries talking in class and entering the classroom after the bell so that his teacher would scold him, but the teacher turns a blind eye to the troublemaking Jonghyeon. In the end, Jonghyeon even gets lessons from Haram on how to become a troublemaker. Then one day, Jonghyeon's mother is called to school, just as he had wished. Jonghyeon's mother slowly changes thanks to his hard efforts, and his grandmother, who had not approved of his mother, at last begins to understand his mother and change. The friendship between Jonghyeon, who saved the warm family love and came to recognize himself as who he is, and the ever charming Haram also grows deeper.

종현이는 학교에서도 집에서도 모범생으로 통한다. 반면 같은 반 친구 ‘안하람’은 말썽꾸러기에 장난을 좋아해 늘 선생님의 시선과 꾸중을 받는다. 종현이는 주부 우울증에 걸린 엄마를 집 밖으로 나오게 하려고 ‘안하람’처럼 말썽꾸러기가 돼 보기로 계획하지만…… 쉽지 않다! 선생님께 혼이 나려고 수업 시간에 떠들어도 보고, 종이 친 뒤에 교실에 들어가 보지만, 말썽을 피우는 종현이를 눈감아 줄 뿐이다. 결국 종현이는 하람이에게 개인 과외까지 받으며 사고뭉치가 돼 본다. 그리고 어느 날 바라던 것처럼 종현이의 엄마가 학교에 불려 온다. 종현이의 말썽 활약(?)에 엄마는 조금씩 달라지고, 엄마를 못마땅하게 여기던 할머니도 비로소 엄마의 심정을 이해하고 변화한다. 따뜻한 가족애를 지켜 내고, 있는 그대로의 자신을 인정하게 된 종현이와 말썽 만점, 매력 만점인 하람이의 우정도 점점 깊어 간다.