Lin McAdam, a former Texas ranger, is riding with his partner High-Spade Frankie Wilson to track down a man. When they reach Dodge City, they run into Dutch Henry Brown, the man they're looking for (though that's not his real name). As Wyatt Earp, the sheriff in town, is keeping a close eye on both of them and has taken everyone's gun, Lin and Dutch Henry confine their bad blood to a shooting contest that's in town; the winner gets the rifle of the title, which is supposed to be the best gun around. Lin ends up winning the contest, but before he can leave town, Dutch Henry and his gang ambush him and steal the gun. At this point, the film follows both Lin's attempt to catch up to Dutch Henry, as well as the path of the gun, as it ends up with a trader, a Sioux Indian chief, Steve Miller, a man trying to settle down with his girlfriend Lola Manners, and Waco Johnny Dean, a cocky gunman, among others.
Notable for being the first film to team up Stewart and Mann (they went on to make seven more films together), the first of Stewart's Darker and Edgier roles, and most important, the first film where a star (Stewart) agreed to take a lesser salary up front in exchange for a percentage of the profits, which helped change business practices in the movies. Rock Hudson and Tony Curtis, who would both go on to be big stars, appear briefly as a Sioux chief and a U.S. cavalryman, respectively.
This film provides examples of:
- Affably Evil: Waco Johnny Dean.
- And This Is for...: A nicer version of this trope: when the army rescues Lola and Steve from the Sioux, Lola kisses Sgt. Wilkes, the head officer for saving their lives; he jokes, "Now you disappoint me; I thought it was 'cause I'm pretty." Later, when Steve and Lola are about to leave, she kisses Wilkes again, and says, "This is 'cause you're pretty."
- Brownface: A young Rock Hudson pops up as Young Bull the Sioux with the prerequisite brown skin tone.
- Cain and Abel: Dutch Henry is really Matthew, Lin's brother, who shot their father In the Back.
- Dead Man's Hand: Dutch notes that he barely avoided one when he gets a third eight and thus a full house.
- Deadpan Snarker: High Spade Frankie.
- Determinator: Lin, all the way.
- Doesn't Like Guns: Wyatt Earp; or, at least, he doesn't like anyone carrying them in his town.
- Historical Domain Character: In addition to Wyatt Earp, there's also reference to Custer getting massacred.
- Hooker with a Heart of Gold: Lola. She gets run out of Dodge City for it.
- I Have Many Names: The reason why Lin initially doesn't realize Dutch Henry Brown is his estranged brother Matthew.Wyatt Earp: I thought you said you didn't know him.
- Last-Second Word Swap: Wyatt Earp would give his ri—his left hand for one of the Winchesters.
- MacGuffin: The gun of the title, though in an interesting subversion, not only do only a few of the characters really want the gun (or know how valuable it is), it's used more as a way to tie the characters together than as a goal the characters are after.
- The Magic Poker Equation: Dutch is dealt a full house; he doesn't even have to draw any cards.
- Redemption Equals Death: Steve.
- Satellite Love Interest: Lola looks gorgeous but doesn't really affect the story very much, the plot being about the gun and the varous people that come in contact with it. Shelley Winters was later quoted as saying "If I hadn't been in it, would anybody have noticed?"
- Smug Snake: Waco Johnny Dean. Lin pretty much cures him of that in a hurry, though.
- Straight for the Commander: "Let's concentrate on the chief," says Lin when the Sioux are gathering for their second attack. Lin then proceeds to shoot Young Bull off his horse, and the leaderless Sioux then disengage.
- What the Hell, Hero?: Lola never really forgives Steve for going for help and abandoning her when the Sioux come riding down on them.