Heroes fight demons. That's about it.

The film tells that Yan Xian's master passed him a demon catcher before he died, but the demon catcher was stolen by the three cat demon. The stranger caught the "demon in the ear" inside the king. Yan Seventeen caught a rat demon who had stolen his money and treasure, and this rat demon named Rat Laibao was the real successor of the demon catcher. 　

A hundred years ago, Immortal Master Yu Xu sealed beasts in eight states, and the Southwest scared tree turned into wilted wood (a spiritual source). In the 40th year of the Zhao Dynasty, Gu Niantong, a perished cult, wanted to break the seal of the Immortal Master, to refine the sacred tree and turn it into a tree demon to poison all living beings. Up till now, the late emperor specially ordered Tang Lingfeng, the hidden supervisor of the Demon Division, and others to command the southwest to pacify the evil spirits. Conquering the tree demon requires the giant beast created by Gong Shujia, and the way to mobilize the giant beast is the "Spirit Source Secret Technique" recorded in "Luban Wiki", ,,