Ji U, an outcast at a prestigious private high school, does not fit in due to his different social background compared to his well-to-do classmates. One day, he meets Hak Seong, the school’s security guard, who is actually a mathematical genius who defected from North Korea, now living with his past shut away.
Ji U asks Hak Seong to teach him math, and although reluctant at first, Hak Seong eventually agrees. Finding each other in their most difficult times, Ji U and Hak Seong open up to one another during their special math lessons, but their friendship is at risk when Ji U is framed for an incident at school, and Hak Seong is faced with people prying into his past.
(Source: Koreanfilm.or.kr; edited by MyDramaLIst)
