Yan Chixia (Louis Koo) is a demon slayer in training who takes upon a journey ordered by his master. His goal is to rid a temple located in the Black Mountain of ghosts who perpetually haunts the shrine. Nie Xiaoqian (Yifei Liu) is a ghost with her spirit trapped by the tree monster. One day Yan Chizia and Nie Xiaoqian meet and fall in love. Yan Chixia learns that their relationship is doomed and, consequently, erases her memory in a effort to avoid killing her. Meanwhile, Yan Chixia watches over Nie Xiaoqian from afar making sure trouble stays away.