Because she lost her mother when she was a child, Han Yun Xi, the daughter of an imperial physician, is perpetually upbeat and optimistic in her outlook on life. In spite of Yun Xi's innate aptitude for medical science and her mastery of traditional medicine, the jealousy and avoidance of others plague her. Her marriage to the Duke of Qin, Long Fei Ye, is an accident of history, and she finds herself thrust into the shifting political landscape of the imperial court. For the Duke of Qin, Yun Xi depends on her medical expertise, wisdom, foresight, and kind heart to expel the poisons of a powerful official, get rid of the disease plaguing the common people, and heal the unusual illness of the crown prince.