The top assassin Fang Ning accidentally missed an assassination attempt on the Prime Minister and was seriously injured and fell into the backyard of the Prime Minister's Mansion. Coincidentally, Lin Xing, the daughter of the prime minister's palace, ran away to protest against the marriage. In the chaos, Fang Ning was treated as a "bride" and stuffed into a sedan chair and carried into the palace of Prince Chenyue, who dominated the court. After entering the mansion, Fang Ning mistakenly took the "childbirth pill" prepared only for concubines in order to detoxify, and her body mutated. He/she has to deal with the uncertain prince Xiao Chenyue, loyal guards and various conflicts. He/she must not only hide the identity of the killer, but also face the dual changes of body and mind. In repeated trials and crises, the cold-faced assassin and the iron-blooded prince sparked unexpected love.
