Undercover High School

A top detective disguises himself as a student to expose a hidden crime ring. As he navigates bullies, tough teachers, and new friendships, he struggles to fit in while uncovering shocking truths about the school.

Hae-seong faces challenges blending in as school rivalries heat up. The student council president grows suspicious of him, while he uncovers new clues about the crime ring. Just as things get tough, an unexpected ally steps in to help.

Tensions rise as the undercover team gets closer to uncovering a hidden secret. Unexpected alliances form, and a shocking twist puts their mission at risk. As friendships and trust are tested, will they stay undercover or be exposed?

The stakes get higher as the team discovers a hidden truth. Suspicion spreads among students, making it hard to remain undercover. A sudden conflict puts their teamwork to test, and an unexpected twist changes everything. Will they adapt or fail?

Hae Seong's cover is at risk as his homeroom teacher, Su A, grows suspicious. While investigating the school, he finds a letter exposing his true identity. A security guard claims to have vital information but is killed before revealing the truth. Hae-sung’s mission takes a shocking turn when he discovers a link to his missing father.

Hae Seong uncovers his father's old notebook, revealing crucial clues. Su A witnesses him in a rooftop fight and pulls a gun, forcing him to confess his true identity. She surprisingly believes him and agrees to help. Meanwhile, Hae Seong realizes Su A is his childhood friend, adding an unexpected twist to their growing alliance.

Hae Seong realizes Su A is his first love, bringing them closer. Meanwhile, the NIS team and Su A investigate the mystery, leading to a high-stakes infiltration of the chairman’s office.

Hae Seong discovers he’s being used by Myeong Ju and that there’s a mole in the NIS. Su A uncovers the grade manipulation scheme, but just as they dig deeper, Hae Seong is abruptly ordered to abort his mission.

The pressure mounts as the agents dig deeper into the school's dark underbelly. A shocking betrayal throws the mission off course, and a mysterious item found in a student’s locker could be the key to unmasking the real villain.

With the school festival underway, the agents face their biggest challenge yet. As hidden agendas collide and the truth surfaces, an unexpected ally steps in—setting the stage for a thrilling and emotional finale.

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, he finally finds closure, but a shocking truth emerges. He learns Director Kim Hyung Bae was behind it all. Determined to uncover the whole story, Hae Seong heads to confront him alone.

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 murdering Director Kim Hyung Bae. After finding out that an arrest warrant had been issued for her, Seo Myeong Ju decides to take a special measure to end everything.