In order to investigate the unjust case of her brother, Xiao Mingyu, Princess Yongning of the Great Zhou Dynasty, faked her death during a palace fire and disguised herself as a man, using the pseudonym "Xiao Yu" to travel around the world. On the way, he meets the knight-errant Lu Jinghong, who mistakes him for a young aristocratic boy and takes him into his sect. The two gradually fell in love while investigating the arms case. When Lu Jinghong discovered that the "little junior brother" who met day and night was actually the princess of the dynasty, the court conspiracy and the grievances in the world had drawn them into a shocking whirlpool...
