On the Lantern Festival's luminous night, Princess Ningyuan died weirdly at the royal banquet. Assigned to this enigma were Li Peiyi from the Inner Surveillance Bureau and Xiao Huaijin, the director of the Imperial Astrology Bureau. Li Peiyi, unmatched in combat and perspicacious in life, aloof but soft-hearted, devoted herself to revealing the truth. To her, each case is more like a match against darkness itself. In the tacit cooperation with the meticulous Xiao Huaijin, they drew out the threads of the cocoon and ultimately dug out the truth and the real culprits through the domineering daughter of a powerful nobleman and the secretive General Lin of the Jinwu Guards. What came later was a storm of bizarre in-palace mystery cases: "Blossoms on Stone", "Crimson Prodigy", "Hour of Ill Omens", and "Seven Stars Unbound", which involved the fate of various females in the palace. During the investigations, they explored the wonders of the Tang Dynasty and witnessed the touching emotions of the world. Gradually, they found out the truth behind the extermination of the Li family fifteen years ago, and ultimately revealed the conspiracy of the masterminds behind the scenes. In these contests, Li Peiyi not only cleared her father's name, but also gained a trustworthy companion and redemption!