"After helping to convict a man of murder, Sam Morgan is troubled, and he races through a blinding storm to the prison where the man, Frank Pierce, is scheduled to be executed at midnight. En route, he picks up a young woman named Ellie and gives her a lift to a nearby lodge. When he is unable to stop the execution, Sam returns to the lodge and joins Ellie for a drink. As the hour of execution nears, she tells him she is Pierce's wife. At midnight, a man named Martinez rushes into the lodge and confesses to the crime for which Pierce is being executed. The next day, after Martinez has been taken into custody by the police, Sam and Ellie go through the last of Pierce's belongings and find a key to a post office box in New Mexico. Certain the box contains money Pierce had stolen 2 years before, they decide to have the money sent to the lodge and divide it."
This neat little noir was released after 1958, which many see as the end of the classic era. It was made on a small budget and utilizes very few sets, making it seem more like a television production than a film (think of "Alfred Hitchcock Presents"), but what I like about it is that we do get a turn from light to dark, and the reason is not what you might expect. Our portagonist becomes disgusted with the criminal justice system and seizes a ready opportunity. He decides that doing the right thing hasn't worked out in his life, so he's going to give the other side a try. Though not classic noir in its denouement, it's interesting to note that black-and-white work of this nature was still being made at this time (see: THE NAKED KISS).
If you'd like to check it out, it's free on Hulu for another 6 weeks or so: