Lim Takhee is a court lady who has stood by the crown prince’s side through countless sleepless nights since their childhood. As the years go by, what started as familiarity evolves into deep affection, and the bond between them grows more intimate than ever. However, everything changes when the crown prince marries his new wife. Lim Takhee grows increasingly anxious as she observes the crown prince, who once couldn’t rest without her, now showing kindness to the crown princess. What will unfold when her anxiety spirals into jealousy, and ultimately, obsession?