While The City Sleeps (1956) by Fritz Lang is late enough in the cycle to be classed as knowing-noir - an almost self-aware example of the medium, that has mastered the tropes, themes, acting style and drama of the film noir phenomenon - enough to package up the groove and bottle it.
While still a classic of the film noir style, many of the more significant tropes which formed the medium in the 1940s are curiously absent. While The City Sleeps is not a film of shadows, and neither is it a production heavy with cigarette smoke, hoods in hats and of course femmes fatales.
Still however, While The City Sleeps is considered by many to be a fine example of classic film noir.
It certainly has an A-list of film noir graduate class of 1956 noir as they come actors in it, including Ida Lupino, Dana Andrews, Thomas Mitchell and Howard Duff.
What makes this journalistic story of a psychopathic killer being caught by the press in concert with the cops a classic of film noir then? Perhaps it is because the story it tells of this killer loose in New York, as told by Fritz Lang, simply in and of itself contains enough material to be a Grade A example of the style, as it stood, towards the end of the cycle.