Turmoil threatens the unity of the Joseon Kingdom in the 15th century. Grand Prince Su Yang has been granted a possibilty to make a coup and raise to the throne, now King Mun Jong has been struggling with his health. The opposition does it's best to stabilize the position of the King's son as rightful heir, while being lead by state councilor Kimg Jong Seo. During this period, there's blooming a forbidden love between Kim Seung Yu (Councilor's Son) and Se Ryeong (Grand Prince Daughter).