Gregory Peck stars as Jimmy Ringo, a relatively old (at age 35) gunfighter in the Old West who wants to settle down. The movie opens by establishing both his speed and his notoriety: he's trying to have a drink in a saloon when a young gunslinger decides he'll prove his mettle by taking on "Jimmy Ringo." This results in the young man's death ... and also three very upset brothers trailing Ringo as he leaves town.
The movie is apparently one of the very earliest that shows that the life of a gunfighter may not have been A) easy, or B) black-and-white. In the town of Cayenne, Jimmy tries to get in touch with his true love Peggy, who's also the mother of his child. On his side is the local Marshal who used to be in his gang - and against him is time, as the brothers will soon catch up with him.
In 2020 this plot sounds like a very conventional Western, but apparently it wasn't at the time. Regardless, it's well done and worth a watch.