Ace NIS agent Jung Hae-seong is demoted after a mission failure. He goes undercover at a high school to locate King Gojong's missing gold, meeting his teacher Oh Soo-ah, who sees him as her lost first love, stirring old heartbreak.
Every episode at a glance, color-coded by rating. Rows are episode numbers within each season, columns are seasons.
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Hae-sung attends the anti-bullying committee session with a key witness who clears his name, while Dong-min finally finds the courage to stand up for himself. With his name vindicated, Hae-sung uncovers the existence of another grandfather clock hidden in the student council room, and the only way to get closer to it is by joining the student council. With the help of his team, he tries to meet the strict requirements.
Hae-sung uncovers a crucial clue hidden within the old building, but Chairwoman Seo quickly learns its potential connection to the elusive gold bars. Sensing the connection, she keeps Hae-sung under close watch. Meanwhile, as Hae-sung delves deeper into the ghost stories surrounding the school, he finds himself caught in the escalating tension between Tae-soo and Dong-min, whose conflict ignites chaos throughout the school.
After uncovering the possibility of a mole within the NIS, Hae Seong becomes increasingly distrustful of those around him, causing him to question the mission's integrity. Meanwhile, Su A exposes a secretive scheme within the school that guarantees top grades for VIP students. As the web of secrets deepens, Hae Seong uncovers the connection between the gold bars and Chairwoman Seo, prompting him to vow to end her sinister plans
After a botched operation puts Hae-sung and his team in serious jeopardy, the only way for him to salvage his career at the NIS is to accept an assignment that seems almost hard to believe. Hae-sung and his team must infiltrate Byeongmun High School, one of Korea's most elite private institutions, to recover ten tons of gold bars worth a staggering 80 million dollars. With everything on the line, Hae-sung puts on a school uniform, and "Operation Undercover High School" begins.
Each point is an episode, plotted chronologically. The colored bands mark season boundaries. Look for upward or downward trends to see if quality improved or declined over time.
Vote count shows how many people cared enough to rate. High votes + high rating = beloved classic. High votes + low rating = notorious stinker. Low votes + high rating = hidden gem.
Episodes plotted by rating vs. vote count. The vertical line marks the rating threshold (7.5). More votes = more engagement. Toggle above to compare against global or show-specific median.
