A top-secret agent transmigrates into Hua Jinyue, the foolish young lady of a marquis's household who has long suffered bullying. Equipped with a magical space that can store objects and armed with modern knowledge, she unexpectedly discovers the Imperial Preceptor Shen Yunian's secret of murder on the night of a palace coup. Holding evidence against him, the two are forced into an entangled relationship, each keeping the other in check. She sets up street stalls and starts businesses to support her family, protects her biological brother, helps the oppressed and vulnerable, and confronts villains wherever she goes. The Imperial Preceptor, a dangerously obsessive man, finds his heart stirred by her unpredictable personality. As the two engage in a constant battle of wits and wills, they join forces to navigate the dangerous power struggles and succession disputes among the princes.