The story tells about the protagonist Jiang Yao, an ordinary college graduate, who accidentally learned that he had died ten years ago while investigating the case of his friend's disappearance. He was also branded with the "Mark of Death" by the underworld for "changing fate" and was hunted by the King of Hell. In order to find out the truth about his friend's disappearance and to escape the pursuit of the underworld, Jiang Yao began to be involved in the dispute between humans and monsters step by step. The demons and monsters that originally existed in the ancient book "Classic of Mountains and Seas" also appeared in modern society. In the process of traveling through the dark world again and again, a conspiracy spanning thousands of years gradually surfaced...