The film tells the story of a "new mission" from the Monster Hall. Faced with a series of mysteries, Xiaohei and his senior sister Luye embark on a new adventure to find the truth.

When cat spirit Luo Xiaohei's home is deforested by humans, he must find a new one. He runs into a group of other spirit creatures who take him under their wing with dreams of reconquering the land they say is rightfully theirs. However, they run into a human known as Wuxian who separates Luo Xiaohei from the other spirits and the two go on a journey, with the cat spirit learning to control his abilities as well as forming his own thoughts on whether or not he should ally with the spirits or the humans.