Kim Shin-rok Returns to School Amid Scandal in Undercover High School

In the latest episode of MBC's drama Undercover High School (언더커버 하이스쿨), Kim Shin-rok's character, Seo Myung-joo, reappears at school after being implicated in a grade manipulation scandal. The episode aired on March 21, 2025, and featured Jeong Hae-seong (played by Seo Kang-joon) exposing Seo Myung-joo's illicit activities.

During the episode, Oh Soo-ah discovers signs of a break-in at Jeong Hae-seong's home and confronts an intruder. When she questions, "Who are you? What are you doing here?" the assailant threatens her with a knife. In the ensuing struggle, Oh Soo-ah is stabbed and collapses, bleeding. Jeong Hae-seong arrives home to find her and urgently rushes her to the hospital, expressing his regret for not being able to protect her.

Once conscious, Oh Soo-ah playfully tells Jeong Hae-seong, "If you're that sorry, treat me better," to which he responds with relief, saying, "Are you okay? I was worried. Thank goodness."

Oh Soo-ah reveals that the mastermind behind the school’s grade manipulation is Lee Jun-ho (played by Noh Jong-hyun). Jeong Hae-seong learns through a phone call that Lee Jun-ho was in his house and had stolen his father's notebook.

Meanwhile, Seo Myung-joo attempts to gain insights into the final rumor but fails. Remembering Jeong Hae-seong's earlier cryptic remarks, she becomes furious, questioning if the answer lies solely with her.

Seo Myung-joo's plan to eliminate Lee Jun-ho through Principal Park Jae-moon (played by Park Jin-woo) fails due to Jeong Hae-seong's intervention. Jeong Hae-seong, who had previously suspected Team Leader Ahn (Jeon Bae-soo), realizes that Ahn is not the traitor he feared, leading him to shed tears of relief.

With Lee Jun-ho's confession, Jeong Hae-seong exposes the grade manipulation scandal, resulting in the arrest of both Seo Myung-joo and Principal Park Jae-moon. It is revealed that the mole is none other than Director Kim (Lee Seo-hwan) from the National Intelligence Service. When Kim attempts to distance himself, Seo Myung-joo laughs, saying, "How far do you think a crazy woman who has lost everything will go?"

Having cleared up the misunderstanding with Team Leader Ahn, Jeong Hae-seong vows, "I will complete Agent Jeong Jae-hyun's mission from 22 years ago. I will find everything, including the gold bars and my father."

The next day, Jeong Hae-seong seeks clues about the final rumor from Lee Dong-min (Shin Jun-hang), who mentions a bizarre school curse that causes those who learn about the last rumor to vanish without a trace.

In the meantime, the absence of Seo Myung-joo brings school inspectors to the hospital. However, both Seo Myung-joo and Principal Park Jae-moon shock everyone by appearing at the school. Seo Myung-joo smiles at Oh Soo-ah, saying, "I heard you almost died. You need to be extra careful from now on."

A startled Jeong Hae-seong rushes to the lobby, where Seo Myung-joo remarks, "We seem to see each other often these days. But it looks like the student games are over," as she rips off his name tag.