A young deputy sheriff stops a cattle baron from rustling the herd of new-comers in the wild New Mexico territory.
Settlers learn that New Mexico is dominated by outlaw cattle barons and turn away. In Santa Fe Gov. Lew Wallace (Berton Churchill) lets John Steele (John Wayne) be deputy sheriff and sends him to Sam Crew. John uses the five-pointed star as his symbol. Cowboy Arizona (Paul Hurst) shoots a man for following his men, and Sam Crew (Noah Beery) says they will change the brands on the cattle. Cal Brett (Lafe McKee) tells his niece Ginger Malloy (Mae Madison) that Sam Crew is going to help them. Her little brother Pat Malloy (Sherwood Bailey) steals elastic from her bloomers for a slingshot.
In the saloon John pretends to be drunk, and Sam Crew pushes him away. Sonora Joe (Luis Alberni) tells Sam Crew that he brought 12,000 head of cattle. Settlers arrive with 5,000 head. Sam Crew secretly sends out Arizona but speaks for law and order. John protects Pat from Arizona, and Ginger thanks him. John tells Cal Brett that he will contact the army about buying his beef. John plays the harmonica. Arizona shoots Cal Brett. During the gun-fight Sonora Joe's men rustle cattle. John makes them leave and rounds up the cattle. Sonora Joe and his men find John cooking coffee. John makes Sonora Joe a deputy to help him arrest Arizona.
At the saloon Sonora Joe drinks with Arizona. John climbs the roof and comes down the stairs to arrest Arizona. Sonora Joe keeps Sam Crew from interfering with the law. They shoot out the lights and take Arizona to jail amid shooting. John's covered wagon is followed by Sam Crew's men while Sonora Joe takes Arizona to Fort Cummings. Gov. Wallace approves. John tells Ginger she is going to marry a deputy. John learns that Major Parker is coming to buy cattle. Sam Crew orders gun-men rounded up. Major Parker says to bring cattle to Fort Cummings. John is abducted, but his horse Duke goes to Sonora Joe. Sam Crew has John tied up and leaves. Sonora Joe frees John, and they pursue Sam Crew, whose men stampede the herd. Ginger falls and is rescued by John. Sonora Joe shoots Sam Crew, who is trampled. John and others turn the herd. In the final scene Ginger and John kiss.
This western drama that shows how efforts for law and order can stop rustling by greedy cattle barons implies that new efforts at law enforcement in the Prohibition era could decrease the problem of organized crime. Faced with an overwhelming problem, John cleverly gets the more amenable rustlers to help his side eliminate the worst criminals.