Su Mu Li, the lord of Fengcheng City, has a dual personality and unstable emotions. In the eyes of the world, she is sometimes kind and gentle, sometimes fierce and treacherous. However, the origin of all this is not known to outsiders. Everyone only thinks that she is moody, so everyone is afraid of this double-faced city lord. Duan Yun Yi, the world's best assassin, does not want the brutal Su Mu Li to survive and is planning to get rid of her. In order to infiltrate the palace and assassinate Su Mu Li, Duan Yun Yi pretends to be Han Zi Ling, and marries Su Mu Li as a cover in order to get close enough to finally take her out. Unexpectedly, this assassin, who had never failed in his action, accidentally discovered Su Mu Li's unknown dual personality. The real Su Mu Li, the one who is kind-hearted, has the same goal as Duan Yun Yi - to get rid of her vicious half.