Ming City Strategy: Suppressing the River Demon

In order to benefit the people, Shen Fu, a wealthy man in the Ming Dynasty, paid for the construction of the city wall. Unexpectedly, during the construction process, the river demon went rampant and destroyed the city wall under construction, and the people were panicked for a while. In order to appease the people, the emperor ordered Shen Fu to present a cornucopia of family heirlooms to suppress the evil spirits, and ordered Shen Fu and Li Hanyang, the left minister of the Ministry of Industry, to repair the city wall within a three-day deadline. The river demon is still killing people everywhere, and Shen Fu and his companions investigate together and discover that there is another hidden reason behind the matter. What kind of shocking secret is hidden behind this? While fighting monsters, how can Shen Fu solve the case within the three-day deadline?