The young prince Ning Xuanzhou became a hostage of the enemy country, and on the first day he was forcibly taken as a roommate by Hua Gongzi. However, Hua Xiyu, who had been forced to dress as a man since she was a child, mistook Ning Xuanzhou, the spy chief, for a princess, and the fake bestie became a real lover. As for the villains who tried to instigate war between the two countries and separate them, they were of course solved by them hand in hand.