The movie "Uncle Maoshan" mainly tells the story of the late Qing Dynasty and early Republic of China. The body of Old Master Ren, a wealthy businessman in Renjia Town, Hong Kong, disappeared after his death. At the same time, a "blood demon" suddenly appeared in the town. "Uncle Maoshan" Mao Xiaofang and his two apprentices assisted Captain Cao Waizui to track down the "blood demon" and uncover the truth.