Yan Shu has had the ability to glimpse the "Shadow Realm" since he was a child, a world parallel to reality and full of distorted echoes and deep shadows. As an adult, he became a "lurker", wandering between humans and the shadow world, working for a mysterious organization to detect shadow creatures that infiltrated reality and preyed on humans. However, Yan Shu's real purpose is not to save the world, but to find his sister who has been missing for many years - she may have already become a part of the shadow world. When a series of strange deaths trigger turbulence at the boundary between the shadow world and reality, Yan Shu is forced to track a self-aware "shadow spirit", only to discover in a cobweb-like mystery that he may be the most dangerous key to the shadow world.
On the edge of fear, he walks between faith and betrayal; in the invisible darkness, every choice echoes the whisper of his sister. Yan Shu must uncover the ultimate secret of the shadow world and the human heart before being swallowed up. Who is the real lurker in the shadows?
