After Xuanwu Gate Incindent, prince Li Jiancheng is killed by Li Shimnin. His daughter Li Changge escapes from the palace and fakes her death during the flee. Li Changge plans to assassinate Li Shimin to revenge her parents. In order to get close to the emperor, she disguised herself as a man and become a military officier. During the war against Tujue Ashinas Sun, she is captured for protecting the people. When be brought to Tujue, she solves lots of problems and conflicts between tribes and rises herself from slave to a counsellor. And she is also attractd by Ashinas Sun and falling love with him.