In the tumultuous backdrop of the Joseon Dynasty, Episode 4 of "The Tale of Lady Ok" delves deeper into the intricate web of secrets and alliances, as Tae-young, now a legal advocate, finds herself entangled with the enigmatic Yun-gyeom and the clandestine Devoted Hearts Association. The episode opens with a tense manhunt, as So-hye and her men scour the land for Gu-deok, while Tae-young hides in the shadows, her survival hanging by a thread.
Yun-gyeom, the unexpected ally, emerges as the calm in the storm, offering Tae-young not just protection but also a startling revelation about his own secret—a physical condition that prevents him from embracing a woman. In a marriage of convenience, Yun-gyeom and Tae-young agree to save each other, binding their fates together in a union that is as strategic as it is unexpected.
As the wedding unfolds, curiosity turns to shock for Seung-hwi and Man-seok, who witness Yun-gyeom's nuptials, while Yuhyangso, or Mother's Sanctuary, seethes with humiliation, plotting the downfall of the Seung family. The political chessboard is set, with each player maneuvering for power and influence.
Yun-gyeom's double life as the leader of the Devoted Hearts Association is revealed, a secret society hidden behind the veil of a gisaeng house, where he and the children he trains bear the mark of 'heart' on their shoulders. Their latest mission is to rescue Moon-soo, a child caught in the crosshairs of a dangerous game.
Meanwhile, Minister Bak's greed leads him to the discovery of gold in Mt. Unbong, and he enlists Scholar Lee Chung-il to oversee the illicit mining operation. However, Lee's wife, Madam Kim, harbors deep mistrust towards Bak, who had previously allowed her husband to be framed and exiled. Despite her refusal, Lee secretly strikes a deal with Madam Hong, trading slave labor for a lavish dowry and a marriage alliance.
Tae-young's legal practice flourishes as she uncovers the deceit of Slaver Ji, who has been tricking the illiterate into selling their children. Her investigation leads to the shocking revelation that Ji and Lee are using these children as miners, including Moon-soo, a noble child sold into slavery after being caught crossdressing.
At home, Tae-young stumbles upon Yun-gyeom's tattoo, uncovering his secret identity and the true nature of the Devoted Hearts Association. As she grapples with this knowledge, she also informs Magistrate Seung about the children, leading to a daring interception of Slaver Ji's latest shipment. In the ensuing chaos, Yun-gyeom, masked and heroic, rescues Moon-soo, but not before his identity is momentarily revealed.
The tension escalates as Tae-young confronts Yun-gyeom about his risky endeavors. He explains the mission of the Devoted Hearts Association—to rescue outcasts and train them in self-defense. That night, a violent incident at the gisaeng house reveals the prejudices of the nobility, as Hae-gang, one of Yun-gyeom's trainees, is attacked for his effeminate appearance. Tae-young's intervention saves Hae-gang, but the incident leads to a trial that exposes the hypocrisy of the noblemen.
In a masterful move, Tae-young cites the King's own actions to argue for leniency, forcing Magistrate Seung to seek royal advice and infuriating the noblemen. Yun-gyeom, grateful for Tae-young's efforts, offers to shut down his operation, but she refuses, understanding the importance of his mission.
As the episode draws to a close, Tae-young discovers the truth about Mt. Unbong and the children mining there. Minister Bak and Lee, fearing exposure, devise a plan to distract Seung by accusing the gisaengs of harboring rebels. In a tragic twist, Hae-gang is killed, and his tattooed body becomes the catalyst for a search that threatens to unravel the Devoted Hearts Association.
In a climactic confrontation, Yun-gyeom is revealed to be Seung-hwi, who had selflessly offered to switch places with his brother to protect Tae-young. As Seung disowns his son, Tae-young stands by Yun-gyeom, refusing to abandon him despite the mounting danger.
The episode concludes with a heart-wrenching scene where Seung, stripped of his position and assets, faints as the provincial governor arrives with a royal decree branding him a traitor. Tae-young, steadfast in her resolve, refuses to leave Seung's side, even as the world around them crumbles.
"The Tale of Lady Ok" continues to weave a tapestry of intrigue, loyalty, and the relentless pursuit of justice, with Episode 4 leaving viewers on the edge of their seats, eager for the next chapter in this epic tale of courage and conviction.