She's on Duty is a South Korean action-comedy film that follows the story of a tough and energetic detective named Chun Jae-in, who is tasked with going undercover as a high school student to keep an eye on the daughter of a notorious gangster.
As she starts attending classes, Jae-in hops from one guise to the next, trying her best to blend in with the teenagers while keeping her real identity a secret. At school, she crosses paths with Hyo-jin, the daughter of the gangster she's trying to get close to. Despite an initial rocky start, the two soon become friends, allowing Jae-in to get close to Hyo-jin and gain her trust.
As the detective struggles to keep up with the demands of high school, she also has to deal with the various problems that come her way, including school bullies, complicated teenage relationships, and gangsters who are on the lookout for her. All the while, she tries to balance her duties as a cop and her newfound friendships with her teenage peers.
As the plot progresses, Jae-in discovers startling truths about Hyo-jin's family, leading to suspense-filled and action-packed scenes that keep the viewers on the edge of their seats. Will Jae-in be able to complete her mission before danger catches up with them? You have to see the movie to find out.