Kim Yoon-seo, a police inspector, returns home to a frightening scene: his brother lies beaten, and his family pressures him to file a false appeal to the King accusing the Lim family, linked to the Deputy Prime Minister. He refuses, choosing integrity over pressure as the elder members of his clan grow increasingly angered by his stance.
Back at court, the King assigns him a critical task. The King’s concubine, Jung-bin, has a painting she believes was copied from her own work, missing only a scribble on the back that revealed the ruse. The King wants Yoon-seo to uncover the culprits, and he is impressed by the originality of the forged piece. Jung-bin is likewise impressed by Yoon-seo’s depth of knowledge about art and invites him to converse more about the subject.
To investigate, Yoon-seo teams up with inspector Lee Gwang-hun, who has a habit of torturing in his dungeons, and they search for leads. They step into a shop where the basement houses an elderly man, a transcriber who is copying an erotic story. Upstairs, a village-affair brawl erupts; Gwang-hun drives the attackers back with his truncheon, while Yoon-seo is knocked unconscious and taken to Gwang-hun’s home. There, Yoon-seo sees the old man’s artistic talent firsthand and gains a wary respect for him. The old man, meanwhile, confesses that he does not wish to shield the mounter, but fears betraying a friend involved in the scheme. He entrusts Yoon-seo with a lead and a place to go, and before leaving, Yoon-seo reads a few verses from the book the old man is reproducing, initially outraged by its pornography but curious about its author’s reputation and the wider appetite of the city. Later, Yoon-seo reports to the King that he has identified the culprits and has them flogged fifty times.
Jung-bin invites Yoon-seo to tea as a gesture of gratitude. A bee lands on her, and in a bold breach of protocol, Yoon-seo moves past the curtain to brush it off her shoulder. Jung-bin does not report the breach and instead expresses warmth toward him. The attraction deepens, and Yoon-seo begins composing an indecent book of his own, which he returns to the shop to have the shopkeeper read. The shopkeeper, Hwang, is impressed, and they decide to copy and sell his work; the book becomes a bestseller.
Seeking greater impact, Yoon-seo asks Lee Gwang-hun to illustrate the newly minted tales. At first, Gwang-hun is furious but eventually agrees. Meanwhile, Jung-bin sends him an embroidered kerchief via her eunuch, hinting at a private meeting if he refuses the gift. He accepts and later secretly meets her in private, where they begin to share a closeness.
The illustrator struggles with certain scenes, so in a subsequent meeting Yoon-seo has the illustrator hide behind a wall to spy on Jung-bin and the concubine during a private moment. Yoon-seo then writes about their affair in his next book. When Jung-bin learns of the affair, she confronts him and demands the name of the illustrator, but Yoon-seo refuses to betray his friend.
Jung-bin finally has Yoon-seo sent to the town prison, a facility overseen by Lee Gwang-hun. In Jung-bin’s presence, Yoon-seo is tied to the ceiling and subjected to brutal canings. Gwang-hun wishes to intervene, but Jung-bin decides to expose the matter to the King. The King asks why Yoon-seo did not lie about loving Jung-bin, and the truth about a deep, forbidden affection remains unrevealed.
The King orders castration to bind him to Jung-bin for life, an act that could kill him given his age. Jung-bin steps forward, taking responsibility for having manipulated him, while Yoon-seo confesses his love in return. Jung-bin tells him they will wait for each other in the next life, and the King, torn by fear and grief, ultimately spares them both, leaving them alive but forever marked.
Exiled to a distant island, Yoon-seo continues to write, while Jung-bin remains at the palace “to rot.” A harsh fate awaits him as the word “indecent” is branded on his forehead as punishment.
The film closes with Yun-seo, the shopkeeper, and their cohort walking along the shore, discussing future projects, including the promise of a homosexual male erotic story and the discovery of the basic principles of animation or “moving pictures.”
