Qi Zhiyu, the Chen'an County Princess who was swapped and sent to the countryside for eighteen years, returns to the Rui Prince's Mansion. As soon as she enters the door, she gives the fake daughter Qi Pingle a humbling blow, then uses thunderous means to outwit the deeply scheming concubine aunt Tang Jingrou and the forces of the Weiyuan Marquis's Mansion, publicly slaps the Crown Prince's faction, step by step exposes the child-swapping conspiracy of that year, protects her mother and two elder brothers, helps her father Prince Rui regain the hope of becoming the heir apparent, battles with wits and courage in the treacherous political power struggle of the capital, and with her own strength reverses the multi-year decline of the Rui Prince's Mansion, protecting the whole family's peace and stability.