University student K is an ordinary young woman, but, one day, she finds herself in her favorite romance novel set during historical times. She has now become the minor character Cha Seon Chaek. She is the daughter of a wealthy noble family and her dream is to have a peaceful and normal life. Cha Seon Chaek, while possessed by K, then spends one night with Lee Beon, the lead male character in the novel.He comes from a royal lineage and is favored by the King. Lee Beon has a cold-blooded personality and is gifted with an attractive appearance and outstanding martial arts skills. He has also experienced a heartbreaking past. Somehow, Lee Beon and Cha Seon Chaek happen to meet and talk. Lee Beon is consoled by her about his heartbreaking past. They spend the night together. Soon, Cha Seon Chaek tries to connect Lee Beon to Cho Eun Ae, who is the lead female character in the novel. According to the novel, Lee Beon and Jo Eun Ae are supposed to fall in love, but, due to the appearance of Cha Seon Chaek, Cho Eun Ae's fate has changed. No matter how hard Cha Seon Chaek tries, Lee Beon’s love always finds its way back to her.Other people around them include Jung Su Gyeom and Do Hwa Sun. Jung Su Gyeom is a young officer from a prestigious family. He is Lee Beon’s only friend. Do Hwa Sun is an ambitious woman whose life goal is to marry Lee Beon and become a member of the royal family.(Source: AsianWiki; edited by MDL)~~ Adapted from the web novel "The First Night With the Duke" (남주의 첫날밤을 가져버렸다) by Hwang Do Tol (황도톨).