Top agent of the NIS and part of Domestic Affairs Team 4. Hae-sung, a top NIS agent, goes undercover at a high school to find Emperor Gojong’s hidden gold and uncover the truth behind his father’s disappearance. Cold and calculated, he sees the school as an obstacle—until he unexpectedly connects with students and becomes a reluctant hero. Torn between duty and newfound bonds, can he still complete his mission?