Li Shimin's eldest son, Li Mu, was framed at the age of five and suffered from hysteria. In order not to affect the struggle for the throne, Li Shimin ruthlessly sent Li Mu out of the palace to deal with it, and announced to the outside world that Li Mu died early and would not be recorded in history. But the then emperor Li Yuan couldn't bear it, so he Let the confidant minister Pei Ji find Li Mu, and foster him in the suburb of Ping'an County near Chang'an City, in the home of a veteran named Qin. From then on, he changed his name to Qin Mu. Until one day, Li Yuan, who was already the Supreme Emperor, found Qin Mu. ... After experiencing the Xuanwumen Incident, Li Yuan swore to the sky: I, the Supreme Emperor, will never show my cards! Until Qin Mu: Old Man Li, why don't we turn against each other...