Duty, honor, bravery - these are attributes of the individual, only when enough individuals carry them, can they define a community or society as a whole, when peer pressure from a majority or a significant number of individuals forces the other society members if not to obtain them, at least to pay lip service to them or to act in accordance with them. Their moral value is very much increased, when individuals display them in the face of a society indifferent or even hostile to them. That is the story of Will Kane (portrayed by Gary Cooper, in what is perhaps his finest role), a marshal in a frontier town, and the story of the 1952 masterpiece High Noon. It is the day of his wedding to a Quacker (played by the lovely Grace Kelly) and the day he gets to resign his commission as marshal and go to another town to open a shop with his new bride: no more gunfights for him, and his wife (who lost a father and a brother to gun-fighting) feels very strongly about it. A new marshal is to come the next day and the town feels it will be safe for a few hours.
After the wedding the town learns that Frank Miller, a killer whom Kane had brought to justice and was originally sentenced to hang (his sentence was commuted to life and he was subsequently pardoned), and his gang of three are coming to town to exact revenge on Kane and take over the town, as they did before Kane's arrival (actually, the other members of his gang are already there and expecting Frank to arrive by the noon train), he decides, at first, to speedily leave the town with his new wife. But it is not long, before his sense of duty overcomes him, and he returns to town, with the intent of raising a posse and facing the Miller gang - he has a little more than an hour until noon to do that (clocks are displayed many times during the film, indicating how much time is left for Kane). His pacifist wife will have none of this and decides to leave with the noon train. One by one, all the townspeople Kane had counted on to assist him either avoid him, or refuse to help - even their wives cannot shame them into it by reminding them the good Kane did for the town. Just one person had initially volunteered and was deputized, only to return his star in the end, when he found out, that there would be no other members of the posse. As for Kane's regular deputy, jealousy and anger because Kane did not support him to become the new marshal leave him out of the fight. There are only two volunteers, whom Kane rejects: the town drunk and a boy who claims to be 16 years old, when he actually is only 14. A subplot involves a Mexican former lover of both Frank Miller and Kane, who has hooked up with Kane's deputy, and has to leave, to avoid Miller's rage for leaving him for Kane. At some point she meets Kane's wife and tells her off for not standing by her man.
In the end Kane faces the Miller gang alone; unexpected help comes from his wife, who, upon hearing the first gunshots, leaves the train (which she had boarded) and goes back to town and even kills one of the brothers. Frank Miller captures her hostage, but somehow she momentarily manages to escape and leaves a little room for Kane to shoot and kill Miller.
An amazing scene follows: the town seemed to be empty during the fight - suddenly scores of people come out of every door, while the 14-year old kid, always looking up to Kane, obliges to get him his baggy carriage. Kane takes his tin star off his vest and throws it down, on the dirt, before leaving town with his wife.
Kane, as an individual, stands out in his community. He has made the town a place for families to live. The saloon owners despise him for that; so do the brothel operators. But those people who are supposed to be the beneficiaries of his actions chicken out and want nothing to do with him. In a climactic scene, in the town's church, Kane is almost accused of provoking Frank Miller into returning back to town. But even after everyone in town refuses to help him, Kane feels bound by his duty and honor. He stays behind to fight for what he believes, even when his wife chooses to leave him, less than an hour after their wedding, rather than stay and see him get killed (though eventually, as we know, she has a change of heart). Although everyone around him displays cowardice, Kane's individual sense of duty and honor keeps him going.
The message of the film should be taken into the context of its time, i.e. the height of the McCarthy era. Many people involved were black-listed at the time and hence not credited with their contributions to the film; but the film displayed amazingly how an individual's core beliefs and values are of more significance than the prevailing societal or political norms.