Moyun Academy is the number one academy in Great Tang. However, it is said that a student of the school will become the catalyst for the return of the King of Demon. To everyone's surprise, a lowlife named Li Xuan is accidentally accepted into the academy. The story is set against the backdrop of the prosperous Tang Dynasty in an era where humans and demons coexisted. The arrival of Li Xuan a human and demon hybrid, breaks the fragile peace. During this time, Li Xuan, demon spy Su Youlian and Long Wei'er develop complicated relationships. As Li Xuan eventually becomes a hero to the people, he faces a dilemma of having to decide where his allegiance lies.