Li Qian, 27, is a graduate student in history at a university, specializing in the Sui and Tang dynasties. His master's thesis is titled "The Deposition of Crown Prince Li Chengqian and the Political Upheavals of the Zhenguan Era." The night before his thesis defense, after working all night revising his draft, he drives home. He swerves to avoid an electric scooter, loses control of his car, and plunges into a river. His last thought before dying is: "If Li Chengqian hadn't rebelled, could he have won?"
When he opens his eyes again, he is in the Eastern Palace in Chang'an, in the ninth year of Wude, and has become eight-year-old Li Chengqian.
He knows that tomorrow his father will kill his elder brother and force his father to abdicate. He knows his fate: "crown prince, rebellion, deposition, death in exile." He also knows that in the future, Li Tai and Li Zhi will take his place. He knows the ending of history, but now he has become one of the people caught up in it.
His golden finger is not a System, but precise foreknowledge of the political situation and historical course of the Zhenguan era. He knows who is loyal and who is treacherous. He knows Hou Junji will embezzle, Li Tai will compile books to curry favor, and Zhangsun Wuji will favor Li Zhi. He also knows when Empress Zhangsun will die and when Li Shimin will campaign against Goguryeo. But he also knows that the more he changes history, the less useful his foreknowledge becomes.
