As the U.S. entered World War II, film noir made its peripatetic appearance. Movies of the film noir ilk were relatively rare and it actually wasn’t until the mid-1940s that this style or genre caught on and an abundance of such movies hit the big screen.
While the film noir style (or genre) borrowed from many sources, it was first inspired by the literary world. Authors like Dashiell Hammett openly criticized the Sherlock Holmes stories as puzzle-solving exercises. For Hammett was “less interested in the solution of a mystery than in portraying his detective hero’s encounters with the evils of modern society in a vivid and compelling fashion.” (According to Out of the Shadows: Expanding the Canon of Classic Film Noir by Gene D. Phillips.)
As Raymond Chandler put it, according to that source, “The solution of the mystery is only the olive in the martini.”
The third major literary influence in creating the film noir craze was James M. Cain.
By focusing on the darkness and corruption their protagonists faced while doing their jobs, these writers took the crime “out of the parlor room and onto the streets.”
You may notice that I refer to the film noir genre or style, as there is controversy among film aficionados about which one it is. If it’s a genre, it’s one based on the conventions of various pre-existing movie genres. And it’s a genre with a distinctive tone, philosophy, cinematography … in short, style. But, without a doubt, it was a style captured well by the early pulp fiction writers, whose lone detectives sought answers down the mean streets of whatever city they were in.