Film noir is characterized by detectives, police, murderers, gangsters, and other shady characters investigating crimes and mysteries in dark, shadowy urban environments. Visual styles include low-key lighting, contrasts between light and dark, and angled shots that enhance the mood of paranoia and suspicion. Common themes include revenge, corruption, greed, and the dark side of human nature. Settings take place at night in places like police stations, back alleys, and seedy underworld locations. Narrative devices employ flashbacks, direct addresses to the viewer, and opening mysteries to draw the audience into the story.