Gu Yun, the legitimate daughter of the Gu family of Jiangnan, excels at identifying fragrances, detecting poisons, and navigating the intrigues of a household. After marrying into the Duke of Zhenguo's household, she finds herself with a gentle and refined husband and a devout mother-in-law who spends her days worshipping Buddha. For two peaceful years, there is no opportunity to put her considerable skills to use. But when her father-in-law brings home a pregnant woman named Liu Ruyan, turmoil once again erupts within the household. Relying on family rules and carefully calculated strategies, Gu Yun exposes Liu Ruyan's manipulative attempts to gain sympathy and firmly maintains control of the household. When her father-in-law's influence in the inner household begins to crumble, he uses his power to suppress the Gu family and force Gu Yun into submission. Refusing to yield, Gu Yun seeks support from outside the household. Her husband, Shen Zhao, also comes to recognize her extraordinary courage and intelligence. The couple transforms their respectful but distant relationship into a powerful alliance, stirring up turmoil among the noble houses and throughout the capital.