While the city of Ankh-Morpork is certainly on the grubby side, it rarely descends into anything approximating noir, except when we are looking through the eyes of Sam Vimes, captain and later Lord Commander of the City Watch.
In the first three City Watch novels, which work as individual police procedural mysteries as well as a fantasy trilogy exploring the idea that monarchy is indistinguishable from villainy,[1] our protagonist appears on the page as the epitome of every crumpled drunk detective who ever brooded his way through a pulp fiction magazine, or the monochrome opening credits of a grimdark TV show.
The difference between Vimes and every other crumpled drunk detective, however, is that the usual noir hero with one foot in the gutter and an endless array of world-weary sarcastic quips is usually immune to narrative change.