S01E01 The Emperor's Lost Gold
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....
Undercover High School
A comic action drama about an NIS agent who hid his identity and entered high school disguised as a high school student to find the missing emperor's gold bullion.
S01E07: The 24th Anniversary of Byeongmun High School
Hae Seong is caught off guard when he recognises Su A's childhood name, Bong Ja, which stirs memories of his first love and distracts him from his focus. Despite the emotional turmoil, Hae Seong pushes forward with the mission to uncover the secrets behind the third ghost story. However, a missing key component forces Su A to join the mission despite Hae Seong's strong opposition to her involvement
Overview
Byungmoon, Korea’s top private high school, is rife with corruption, where status and success matter most. Hae-sung, a top NIS agent, goes undercover at Byungmoon 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 connects with students and a former crush and becomes a reluctant hero. Torn between duty and newfound bonds, can he still complete his mission?
Episodes
S01E02 Spooky Stories
Hae-sung comes dangerously close to blowing his cover while searching for the hidden gold in Byeongmun High School's eerie old building, barely escaping detection by Soo-ah, his sharp-eyed homeroom teacher. As he hears chilling rumors...
S01E03 Ghost Story Riddles
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...
S01E04 Joining the Student Council
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...
S01E05 Student Council
Hae Seong and the team grow increasingly concerned that Su A's suspicions could threaten his undercover mission. However, Hae Seong defies the odds and successfully gains a spot in the student council. With this new...
S01E06 Hye Seong's Father's Notebook
The school's security guard dies, leaving Hae Seong a notebook belonging to his missing father. The revelation is shocking, and he storms the NIS for answers. The answer pushes him away from the mission, and...
S01E07 The 24th Anniversary of Byeongmun High School
Hae Seong is caught off guard when he recognises Su A's childhood name, Bong Ja, which stirs memories of his first love and distracts him from his focus. Despite the emotional turmoil, Hae Seong pushes...
S01E08 The Plan for VIP Students
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...
S01E09 The Mathematics Teacher
As Su A recovers in the hospital following the attack during the break-in, Hae Seong and the team uncover the culprit: Lee Jun Ho, the mathematics teacher. When Hae Seong detects his father's notebook missing,...
S01E10 Retribution
To everyone's shock, Seo Myeong Ju returns to the school. Unimpressed by Hae Seong, she expels him and demonstrates her power by dismantling his team. However, refusing to back down, Hae Seong and the team,...
S01E11 The Devastating Truth
The gold bars vanish just as they are within reach, and Seo Myeong Ju suspects Hae Seong has them. In the vault, Hae Seong makes a heartbreaking discovery of his father's remains. Overcome with grief,...
S01E12 Where The Stars Lead
Despite getting badly injured, Hae Seong manages to call Su A and his team. They conclude that the only evidence they can secure is the flash drive that contains the voice recording of Principal Park...
Cast
Seo Kang-joon
Jeong Hae-sung
Jin Ki-joo
Oh Su-ah
Kim Shin-rock
Seo Myung-ju
Kim Min-ju
Lee Ye-na
Yoon Ga-i
Park Mi-jung
Kim Young-ah
Im Chung-ha
Lee Hyeon-so
Han Seung-jae
Kim Seung Beom
Kim Ho Jin [Informant]
