On March 21 & 22, 2025, MBC aired episodes 9 and 10 of the thrilling series Undercover High School, featuring performances by Seo Kang-joon and Jin Ki-joo. The drama revolves around Jeong Hae-seong (played by Seo Kang-joon), an NIS agent disguised as a high school student, who embarks on a mission to locate gold bars valued at 800 million KRW.
Jin Ki-joo brings depth to the character of Oh Su-ah, Jeong Hae-seong’s homeroom teacher, whose suspicions about him often clash with a series of personal connections, including a resemblance to a beloved figure from her past elementary school days.
Recent Episodes Recap: Episodes 9-10
In episode 10, the tension escalated when school director Seo Myeong-joo leaked a scandalous image of Oh Su-ah and Jeong Hae-seong enjoying drinks at a restaurant bar. This malicious act was intended to tarnish Oh Su-ah’s reputation among the school’s students and staff. However, Lee Ye-na stumbled upon the images on Seo Myeong-joo’s tablet and quickly informed Jeong Hae-seong, plunging him into a moral dilemma.
Upon learning of the photos circulating, Jeong Hae-seong rushed to the school to clarify his position to his peers, insisting that he was not a minor. As he nearly disclosed his identity as an NIS agent, he was deterred by Oh Su-ah and Ahn Yu-jeong’s gestures, leading him to fabricate a story about wanting to earn his high school diploma, while openly admitting his feelings for Oh Su-ah.
Unraveling Mysteries: Jeong Hae-seong’s Quest
In the earlier episode 9, Jeong Hae-seong took decisive action by escorting Oh Su-ah to the hospital after she was attacked by an intruder, later identified as math teacher Lee Joon-ho. Under duress from Seo Myeong-joo, Lee had attempted to retrieve Jeong’s notebook, stirring a web of deception within the school.
As events unfolded, Lee Joon-ho confronted Seo Myeong-joo, vowing to cease manipulating student grades. With mounting tension, Jeong Hae-seong’s NIS teammates, Go Young-hoon and Park Mi-jeong, surveilled principal Park Jae-moon, leading to a rescue operation that ultimately placed Jeong in the spotlight.
Following a series of escalating confrontations, Seo Myeong-joo was arrested for her involvement in the corruption scandal. The revelation of Kim Hyung-bae, the NIS director, being the mole further complicated the matter, prompting the school community to brace for an investigation from the education authority.
In a shocking turn, Seo Myeong-joo resurfaced at the school, leading to Jeong Hae-seong’s unexpected expulsion. At the same time, a sudden search of the NIS department dismantled Jeong’s team. Nevertheless, Jeong suggested they regroup at his home to continue their critical mission. He discovered that the final piece of the mystery—the legendary gold—was linked to his missing father, Jeong Jae-hyun, who had vanished two decades earlier during a similar mission.
As the team pieced together clues, they were drawn to a bust statue, which they managed to open, only to be thwarted by the vice principal just as they were about to uncover critical evidence. Meanwhile, Oh Su-ah’s mother, Im Chung-ha, disclosed her own hidden past of gang affiliations and offered assistance, rallying her old contacts to support Jeong’s cause.
In the gripping finale of episode 10, Jeong Hae-seong and his team infiltrated the school under the guise of an NIS operation, facing opposition from Seo Myeong-joo. While she attempted to contact Kim Hyung-bae for verification, he was conveniently preoccupied with a game of golf, allowing Park Mi-jeong to create a diversion.
As Jeong accessed the underground compartment behind the bust statue, he encountered a chilling discovery: a human skeleton wearing his father’s watch. The episode concluded with Jeong Hae-seong overcome with emotion, marking a poignant moment as he confronted the reality of his father’s fate.
Undercover High School, featuring Seo Kang-joon and Jin Ki-joo, airs every Friday and Saturday on MBC, providing viewers with an engaging mix of suspense, intrigue, and emotional depth.