Xie Si, a modern police profiler obsessed with Cthulhu Mythos, falls asleep after staying up all night studying a bizarre case file. When he wakes, he finds himself transmigrated to "Fog City," a Victorian-style metropolis that is almost, but not quite, like his hometown. Stranger still, on the night he arrives, a second moon appears above Fog City: a pale, motionless orb that looks like a mirror, known as the Mirror Moon.
Drawing on a profiler's keen instincts and the "information gap" afforded by being from another world, Xie Si quickly realizes that this world has been infiltrated by indescribable beings. He assumes the identity of a detective who suffered a mental breakdown while investigating a missing persons case, and reopens the investigation
