The soul of modern historian Shen Yan traveled through the prosperous Tang Dynasty and became the despised concubine of the Boling Shen family. With the prophet of history, he carefully survives in the prosperity and undercurrent of Chang'an. At a palace banquet, he encounters Li Mingyue, the princess of Le'an who is investigating the truth about his father's death.
From the whirlpool of party strife in the court to the flames of An Lushan's rebellion, the two went from testing their trust to breaking up due to their positions, and then reunited amidst the national disaster of the Anshi Rebellion. Shen Yan experienced the rise and fall of his family and the death of his relatives. In the struggle of "knowing that history is hard to change", he transformed from a bystander of history to a participant in protecting the people; Li Mingyue also put aside personal hatred and joined hands with Shen Yan to protect the people.
In the end, Chang'an was recovered, Shen Yan chose to stay in office and rebuild, and Li Mingyue went to Hebei to quell the chaos. This round of Chang'an Moon, which shined in the glory of the prosperous Tang Dynasty, finally witnessed the story of individuals maintaining the warmth of human nature in the torrent of the times, amid the righteousness of family and country, and love and hatred.
