Kang Hyeon-joong, a former National Intelligence Service agent, is currently running a private investigator office after he quit his previous job. Han Mi-so is his secretary helping him with his daily tasks in the office. One day, Kim Jin-hee comes to the detective’s office and requests him to investigate all the women who follow her husband around.

Kang Hyeon-joong, a former National Intelligence Service agent, is currently running a private investigator office after he quit. Ha Mi-so is his secretary helping him with his daily tasks in the office. One day, a woman whose name is Yoo-ra visits the office and requests him to investigate about a man named Min-ho, whom she loves. She wanted to know what Min-ho really thinks about her. She says she is scared and concerned that he might think she approached him because she wanted the assets of his wealthy family. So she wanted to confirm if he actually loves her. In the afternoon on the same day, Min-ho comes to the same office and makes a request to investigate about Yoo-ra’s inner thoughts. Kang Hyeon-joong is perplexed as he received the same request from a couple separately on the same day. But he shortly realizes there is something strange in the stories from both of them and this situation is all because of a plan someone has plotted deliberately.

Tae-seong, a mixed martial arts professional with excellent skills, is injured and got disqualified as he gets caught up in a fight with his friend Byeong-jin inside a store ahead of his UFC debut. Hye-na, Byeong-jin's younger sister and BJ professional in mixed martial arts, encourages Tae-seong to make a comeback, but Tae-seong refuses. Hye-na finds out that the man who injured Tae-seong is Yang Ho-yeol, the strongest champion of "Blood Street", an illegal gambling game site where one can bet after a real street fighting match, and she informs Tae-seong about it. Tae-seong jumps into "Blood Street" for revenge. "Blood Street" users go wild, calling masked Tae-seong a "real fighter". Tae-seong and Ho-yeol break "Blood Street" and start a fight to be the real champion!

Detective Agency: Face of the Gnome is the third episode of the melodrama, crime and thriller Korean movie series. The first one is Detective Agency - Love and War 2016 (탐정사무소 - 사랑과 전쟁). The unknown Jin finds out the detective office and asks Hyun-chae to investigate why his wife committed suicide. And it tells that the cause of Seonye is related to the inner part of Seonyun. Hyun Jung, who visited the South, finds out that the camp is hiding something from his statement. And I know Jinhui, a college alumni and psychotherapist. Hyun-jung knows that Jin-hee is a hypnosis specialist and feels that this event is related to hypnosis. Hyun-jung persuades the camp and goes to Jin-hee and starts to run down the things that happened on the day of the incident. After all, Jinhei starts to reveal the truth of all the events.