"Dark Room" tells the story of a major naked loan crime case that occurred in Tianan City, Beijin Province. The city's criminal police began their investigation with a murdered security guard. Through hardships and bloodshed, they finally wiped out the criminal gang that used nude loans to extort, force prostitution, and murderes, and dug deeper to find the hidden leader of the gang, "Cuttlefish," who was arrested and brought to justice.