The story takes place in the middle period of the fictional "Dayong Dynasty" (corresponding to the transitional style between the Tang and Song Dynasties in real history). The capital is "Shangjing", and the territory reaches the East China Sea in the east, Yumen Pass in the west, Lingnan in the south, and the grassland tribe "Canglang Tribe" in the north. At this time, the Yong Dynasty had been established for more than a hundred years. On the surface, it was singing and dancing, but in fact, there was an undercurrent: the imperial power was falling aside, and "Wang, Xie, Li, and Zhao" The four major aristocratic families headed by them monopolized half of the official positions in the court; the local feudal towns secretly accumulated power, and salt merchants in the south of the Yangtze River and grain merchants in Shu colluded with the aristocratic families to form an interest network; the Canglang tribe on the border went south to plunder every autumn. Although the Zhenbei Army resisted vigorously, they were often in trouble because of the deduction of food and salary; in addition, there were also secret forces such as the "Secret Medicine Workshop" and "Shadow Pavilion" in the rivers and lakes.
