Xie Si, a police profiler from modern times who is obsessed with the Cthulhu mythology, fell asleep after staying up late to study a bizarre file. When he woke up, he found that he had traveled to a Victorian-style city called "Fog City" that seemed different from his hometown. What's even weirder is that on the night we traveled, a second moon appeared over the foggy city—a pale, still, mirror-like "mirror moon."
Relying on the profiler's acumen and the traveler's "information gap", Xie Si quickly realized that the world had been infiltrated by unspeakable beings. He took on the identity of a police detective who suffered a mental breakdown while investigating a disappearance and re-entered the investigation.
