Lee Hak-sung was a genius mathematician in North Korea. He defected to South Korea and now works as a security guard at a private high school. A student who is about to give up on math discovers Hak-sung's real identity and asks Hak-sung for help. While guiding Ji-woo to find the correct answer, Hak-sung is slowly embracing an unexpected turning point in life.
Lee Hak-sung was a genius mathematician in North Korea, but he defected to South Korea and now hides his past life. He works as a security guard at a prestigious private high school. However, students in the high school stay away from Lee Hak-sung due to his frosty manner. A student named Han Ji-Woo who is on the verge of giving up on maths, chances upon Hak-sung's real identity. Circumstances lead Ji-woo to ask Hak-sung for help. In the process of guiding Ji-woo to find the correct answer, Hak-sung is slowly embracing an unexpected turning point in life without him knowing.
