Shangguan Yi, the legitimate daughter of the General's Mansion, has been traveling around the capital in men's clothing as a "Happy Young Master" all year round to establish an underground intelligence network in order to investigate the truth behind her brother's unjust case on the battlefield. She accidentally met the idle prince Gu Zhixuan because of a "hero saving a beauty", but she didn't know that he was the "man in the game" she had been looking for and held key evidence. While investigating a huge conspiracy sweeping the government and the public, the two went from testing each other to fighting side by side, and finally revealed the truth. She also changed from a "fake princess" to a legitimate real princess, and together with Gu Zhixuan, she protected her family, country and world.
