In a city shrouded in haze, a series of bizarre and horrifying cases broke the calm. Young detective Xiao Ming, senior detective Lao Zhang, brave reporter Xiao Mei, witty police officer Xiao Lin and experienced criminal police captain Lao Wang are brought together by their persistent pursuit of justice.
Xiao Ming is responsible for the mysterious death case in a remote town, and each victim has a mysterious smile and receives a mysterious letter; Lao Zhang is responsible for the urban disappearance case, and the missing persons have been to the abandoned factory shrouded in fog; Xiao Mei is exploring the "cursed house" that is full of weirdness; Xiao Lin is assisting in the investigation of the death of an artist, and the puzzle pieces at the scene hide important information; Lao Wang is responsible for the disappearance of a woman, and her family received a mysterious letter pointing to an unsolved case many years ago.
During the investigation, they discovered that there was a huge conspiracy involving powerful people, gangs and mysterious organizations hidden behind the case. During this period, they met many people with different identities, such as grocery store owners, old workers, women living alone, etc. Everyone seemed to have secrets.
They had targeted several suspects, but found that the clues were constantly interrupted and they were in many difficulties. But they never gave up, and continued to conduct in-depth investigation and reasoning, trying to uncover the truth behind it and save the city from darkness.
