Yan Chixia (Louis Koo) fell in love with Xiaoqian (Liu Yifei) when he was young, but due to his responsibility as a demon hunter, he could only reluctantly give up. He did not kill Xiaoqian, but made her lose her memory. He and Xia Xuefenglei (Fan Shaohuang) teamed up to deal with the Black Mountain Old Demon (Kara Hui), who sacrificed his left arm to seal the old demon. One day, Ning Caichen (Yu Shaoqun) was sent to Heishan Village to help the villagers find water. The village chief (Elvis Tsui) and others knew that there was a demon on the mountain, but they did not tell him the truth. Accompanied by the villager Tieya (Li Jing), Ning Caichen took a group of death row prisoners to the mountain to find water. When they came to Lanruo Temple, they found a water source. And he also met Xiaoqian for the first time. The two fell in love at first sight. The Black Mountain Old Demon learned about this and tortured him severely. Yan Chixia repeatedly dissuaded Ning Caichen from falling in love with a human and a demon, but the latter had a deep affection for Xiaoqian. Knowing that she was a demon, he repeatedly took risks and had no intention of retreating. Yan Chixia felt conflicted, and at this moment the Black Mountain Old Demon had already begun her revenge...