To pay for his mother’s medical expenses, the hunter A-Ming is forced to risk entering the Spirit Mountain during the "Blood Moon" closed season. Unbeknownst to him, he has fallen into a trap set by tomb raiders Zhang Qiang and his wife. Using the guise of buying game at high prices, they lure him into repeatedly breaking mountain taboos—such as "never kill a pregnant beast"—using him as a "live bait" to find an ancient tomb guarded by a "Shan Xiao" (mountain spirit). After breaking these taboos, strange incidents plague him. Each time he nears death, he is saved by the mountain warden, Lao Jin. Lao Jin painfully reveals that his own son died due to similar taboos and urges A-Ming to put down his gun. With his mother's health improving, A-Ming plans to quit hunting. However, Zhang Qiang and his wife, disguised as siblings, are unwilling to let their plan fail. Zhang’s wife, Xiao Li, uses seduction and exploits A-Ming’s sense of responsibility to force him back into the mountain. Faced with more supernatural horrors and intense pressure, a panicked A-Ming accidentally crashes into the entrance of the ancient tomb. Waiting for him is the cold barrel of Zhang Qiang's gun and a cruel truth: he was merely live bait to "lure out" the tomb and a scapegoat to be silenced. In this desperate situation, Lao Jin appears and reveals the source of all the bizarre phenomena: his son had been lured by the couple years prior to find the tomb; when he tried to stop them, he was nearly murdered and fell off a cliff, losing his sanity and becoming the "Shan Xiao" of the forest. Grief-stricken and fueled by rage, Lao Jin used his knowledge of the mountains to spend years acting as the "Shan Xiao" alongside his son, creating horror legends just to warn the world to stay away from the tomb and to seek revenge for his son.
