Foreign envoy Ye Qianyao came to pay tribute with the divination prophecy that "whoever gets Dugu gets the world". The emperor sent Zuo Zhaoyi Yinshi to receive them and agreed that they could visit Chang'an at will during their visit. During this period, they met the great general Dugu Xin. At the same time, the emperor saw the divination prophecy of "Dugu's world" and felt uneasy, so he summoned the immortal Xuan Longzi to interpret the prophecy. What followed was a series of bizarre cases involving Zuo Zhaoyi and other court officials. It turned out that the real delegation had already encountered and killed halfway, and Ye Qianyao, who was exiled due to an unjust case, took the opportunity to pretend to be an envoy of a foreign country in order to return to Chang'an to find out the truth about the death of his father. Dugu Xin, as the leader of the Chang'an spy organization Jinlinshi, accepted the emperor's secret order to investigate the case, and teamed up with Ye Qianyao to continuously explore the truth. As the case deepened, the mystery of the double-headed illusion was finally revealed, the crisis was resolved, and the court and all living beings were saved.