During the Kaiyuan period, undercurrents surged in Chang'an, and the power struggle between the prince and Princess Taiping became fierce. {Shen Yan}, editor of the Hanlin Academy, was demoted as a tax collector in the West City because his father was framed and involved in a rebellion. In order to clear his father's wrongdoing, he secretly investigated and unexpectedly discovered that there were clues in the case containing secret letters that would affect the court. Shen Yan relied on his resourcefulness to travel among various forces: he teamed up with Jing Zhaoyin to solve the smuggling case and was appreciated by the prince; he used his chess skills to make friends with the advisers of Princess Taiping and spy on the news. On the way, he met Su Qiniang, a female ranger with superb disguise skills. From testing each other to fighting side by side, he gradually uncovered the shocking conspiracy of the eunuch and his relatives. In the end, Shen Yan presented irrefutable evidence at the court meeting in Hanyuan Palace to clear his father's grievances and help the prince stabilize the court. However, he chose to retreat to the south of the Yangtze River and leave a legend like playing chess in Chang'an.
