Shen Jintang, the legitimate daughter of the Duke of Zhenguo, appears to be a frail and sick medicine pot, but is actually a "behind-the-scenes chess player" full of wit and scheming. Xiao Jingxuan, the eldest son of Prince Qi, appears to be a romantic and unrestrained dandy, but in reality he is the Emperor of the Dark Night who bears a blood feud. A sudden decree of marriage tied two childhood sweethearts wearing the thickest masks together. They went from being a "drama queen" couple who tested each other to being soul mates who worked together to investigate the case, clear up the dynasty, and bring justice to the family. In the turbulent power struggle, they are each other's only light and each other's sharpest edge.
