High Noon is plainly About Something — as you can tell from the opening credits. Men like producer Stanley Kramer (Inherit the Wind (1960), director Fred Zinnemann (From Here to Eternity (1953) and writer Carl Foreman (Champion (1949)) were strangers in the sagebrush, but had ambitions to make Academy Award-type pictures, movies that tried to deliver some sort of content along with the shoot 'em up stuff.
Gary Cooper, the top-billed star, was a familiar cowboy face with a western drawl to match, but he was in his third decade as a revered movie star, a little elderly for the rough stuff and with acting chops to spare. The innovation of High Noon is that it's significant, but not big. Its understated but unforgettable opening — three bad men (Lee Van Cleef, Robert Wilkie, Sheb "Flying Purple People Eater" Wooley) at the station, waiting around on a Sunday morning while Tex Hitter's ballad explains the plot — prefaces a movie that takes place almost in real time, from mid-morning to just after midday, and never strays far from the main street of the western township of Hadleyville.
In the 1940s and 50s, high-stakes westerns were inclined to the epic, with Technicolor mesas and deserts and hordes of cowboy and Indian extras, but High Noon could be a TV script. Its style is like that character-and-suspense-based drama which would evolve when American television was broadcast live from New York. The simmering resentment of sidelined Deputy Pell (Lloyd Bridges) that his soon-to-be-ex boss, retiring Marshal Will Kane (Cooper), didn't get him appointed the new law in town pays off with a fistfight at the halfway point, but otherwise the film is all about suspense rather than action. Guns aren't drawn in anger until the last five minutes, when the streets are clear for one of the best gun fights in the movies.
The plot nugget is that just as Kane has married Amy (Grace Kelly) and handed in his star, Hadleyville learns that Frank Miller (Ian MacDonald), the villain who used to run the place, has been pardoned by, "them Northern politicians". Miller is due in on the noon train to keep his promise to gun down the man who sent him to prison. Kane takes back the badge, but is shocked to learn no-one will stand by him: some of the townsfolk have gone soft since the wild days ended, others yearn for the lawlessness Miller will bring back, some resent Kane for real or imagined slights, others try to tell him it's not worth getting killed for people who won't stand up for themselves, and his new wife is a Quaker prepared to forsake him.
Cooper, in agony from a bad back during shooting, is remarkable, conveying the inner pain of a man who learns that his earlier heroism no longer counts. In effect, High Noon is a sequel to an unmade earlier film about the town-taming he-man and the baddie he bested. Many films based on the legend of Wyatt Earp — Law and Order (1932), Dodge City (1939), Frontier Marshal (1939), My Darling Clementine (1946) — had told this story of the bringing of civilisation to the wilderness. Hadleyville is the neatest, most domesticated town in western movies, complete with nice white church, opera house (Mazeppa is playing), trains that run on time and folks who can hardly remember, "when it wasn't safe for a respectable woman to walk in daylight". The film shows the happy endings of earlier westerns were sham: the savage outlaws can come back at any time, and the extras who benefited from law and order decide they'd rather be kicked around by Miller than shot dead. This enraged Howard Hawks and John Wayne, who responded with Rio Bravo (1959), in which a Marshal turns down offers of help because he's being paid to do a job and doesn't want innocents killed.
Wayne was proud of getting the blacklisted Foreman kicked out of America in revenge for the "un-American" gesture that ends High Noon, though when the Duke was handing Cooper a Best Actor Oscar he said he wished someone would write him a western part as good as Will Kane. Many commentaries on High Noon have assumed that it's making a statement about the bullying tactics of Senator Joe McCarthy, which exposed a wide streak of gutlessness in many Hollywoodites. However, it's possible McCarthy might have seen the film as an endorsement — identifying with Cooper, a real-life supporter, and thinking of the townsfolk as the fellow travellers and liberals whining about his crusade against creeping subversives like Frank Miller.
The film pays off with four bad men deservedly dead, the Marshal (and his now gun-toting wife) still standing, the townsfolk hanging their heads-in embarrassed shame, and (as in Dirty Harry, 1971) the badge tossed in the dirt.