In 907 CE, during the rise of the Later Liang dynasty, Yuan Qing Li—the daughter of a general—sets out for a peaceful retreat at a nunnery. But when her journey is violently interrupted by bandits, she is left unconscious and rescued by strangers. Awakening with no memory of her past and facing an unwanted arranged marriage, she escapes and disguises herself as a man. With her martial arts skills, she quickly rises to become a county constable.

At the same time, Duke Jing Ci, undercover as a humble official, is working to uncover a dangerous conspiracy threatening the government. As their paths cross, the two join forces to fight corruption—and help Yuan Qing Li unlock the secrets of her true identity.