The First Night with the Duke

University student 'K' finds herself magically transported into her beloved novel "The Obsessive Tyrant", where she takes on the role of Lady Cha Seon Chaek, the only daughter of the Chief State Minister. She had dreamed of being a quiet observer, simply witnessing the romantic tale between Prince Gyeong Seong and Cho Eun Ae unfold. However, during the night of the Dahong Club's meeting, an unexpected turn occurs. When she awakens the following day, she discovers she's lying next to Prince Gyeong Seong!

By chance, Seon Chaek meets Bun and ends up spending the night at his place. The next day, Bun wishes to rush to arrange a wedding with Seon Chaek, but Seon Chaek has no intention of marrying him. She begins plotting clever ways to escape the situation. Will Seon Chaek's plans succeed? Meanwhile, she finds herself threatened by thugs in the woods. That's when a mysterious man suddenly appears to help her.

To set her story back on course, Seon Chaek orchestrates a gathering to unite the intense Lord Lee Bun with his intended match. But her elaborate scheme hilariously backfires, only fanning the flames of his dangerous obsession with her instead. Now, she's trapped in a new chapter she never meant to write.

Bun shocks everyone in the Astral Philosophy Club by announcing that he's going to marry Sun Chaek. To make matters worse, Bun goes to Sun Chaek's family and claims that she took his innocence and that is the reason they must get married. However, Sun Chaek's father firmly opposes the idea.

Resolved to bet her fate on Yi Beon, Seon Chaek bravely enters the treacherous royal bride selection. Just as she commits to her path, Su Gyeom reels from the shocking news that Eun Ae is also a candidate. The game for Yi Beon's heart has just become dangerously complicated.

Beon gets close to Hwa Sun in order to enter the Do family's house and snoop around inside to find evidence regarding the foreigner. Meanwhile, Seon Chaek feels lost about how to tackle the assignment given by the Queen Dowager, but after witnessing the struggles of farmers suffering from a bad harvest, she suddenly gets an idea. 

Lee Beon creates a perfect romantic day for Seon Chaek, proving their love can overcome any obstacle thrown their way. Their fairytale moment is destroyed by the arrival of Lee Gyu, a charismatic stranger who claims a prior right to Seon Chaek's hand. He built a perfect world for her, only for another man to tear it down.

While sharing a moment of affection with Lee Beon, Seon Chaek is caught by her father and is promptly grounded. Meanwhile, the King grows suspicious of Lee Gyu's sudden return to Hanyang. Meanwhile, Bun makes every effort to earn the favour of Seon Chaek's family. Beon's first target is Seon Chaek's brothers.

Yi Beon's desperate rescue of Seon Chaek should bring them closer, but a new mystery tears them apart. When the kidnapper's body appears in public, Seon Chaek confronts a horrifying truth about the man she loves. She is safe in his arms, but she may be in love with a monster. 

Su Gyeom confronts Eun Ae, asking if she's the one who wrote the letter that led Seon Chaek into the trap. Determined to clear her name, Hwa Seon decides to find the real culprit herself. Bun presses Eun Ae to reveal who her accomplice is, but she refuses to give in easily. Seon Chaek asks Yi Gyu to step in and help Bun out of his predicament. 

Seon Chaek seeks out Sul Gi to ask about the identity of the wooden doll, but Sul Gi draws a fortune that even she struggles to interpret. The King fears that the Black Gang might come after him while Yi Beon is away from the palace. While Yi Beon is away and the King grows weaker, Yi Gyu begins to undermine him.

Yi Beon miraculously finds his way back to the Palace. Yet, the King, shaken to his core, believes it is Yi Beon's ghost that is haunting him. Meanwhile, Seok Chaek asks Eun Ae, her favourite character, when she started becoming so cruel, and Eun Ae answers without hesitation that this is who she has always been.