Undercover High School, one of the most popular action K-dramas of 2025, concluded with a thrilling finale that answered fans’ burning questions. The series follows National Intelligence Service (NIS) agent Jeong Hae-seong, played by Seo Kang-joon, as he goes undercover as a high school student to recover Emperor Gojong’s missing gold. Directed by Choi Jung-in, the show became one of the highest-rated K-dramas of the year, garnering praise for its engaging plot and action sequences.
Strong Ensemble Cast Drives Espionage and Justice, Revealing Villains’ Crimes Finally
The drama features a strong ensemble cast, including Seo Kang-joon as Jeong Hae-seong, Jin Ki-joo as Oh Su-a, Kim Shin-rok as Seo Myung-joo, and Lee Seo-hwan as Kim Hyeong-bae, among others. Each character plays a significant role in the unfolding story of espionage, betrayal, and mystery. Seo Kang-joon shared that his role allowed him to portray a new side of himself post-military service, expressing gratitude to fans who connected with his character.
Undercover High School (Neo Entertainment)In the finale, Hae-seong successfully exposes the antagonist Seo Myung-joo. After being framed for the murder of NIS director Kim Hyeong-bae, Hae-seong presents a recording proving the real culprit was Myung-joo’s subordinate, Park Jae-mun. This revelation leads to both Myung-joo and Jae-mun being arrested, with Jae-mun testifying against Myung-joo, who is ultimately sentenced to life in prison for her crimes.
Hae-seong Finds Hidden Gold and Finally Achieves Closure With Su-a
Hae-seong also completes his mission of finding the hidden gold, which had been concealed by Seo Byeong-mun during Korea’s Japanese occupation. The gold was hidden in Byeongmun High School, where Hae-seong discovers it beneath the attic floorboards, following a clue from his late father. This closure allows Hae-seong to honor his father’s memory, bringing both personal and professional resolution to his mission.
The series concludes on a positive note for Hae-seong and his love interest, Oh Su-a. After successfully completing his mission, Hae-seong and Su-a enjoy time together, culminating in a heartfelt proposal, which Su-a happily accepts. The finale thus ties up both the action-driven plot and the emotional arcs of the main characters, leaving fans with a satisfying ending.
