When a trail herder's father is murdered, he becomes sheriff to bring law and order to a new town.
In 1889 President Harrison opens the Cherokee Strip to settlement. Milt Dawson (Sam Flint) urges his son John Dawson (John Wayne) to go into ranching, but John is trail herding. Horsemen and wagons rush for land. A new town has a church and a saloon dance-hall. There Ace Holmes (Warner P. Richmond) shoots a man for cheating at cards. Tom Lewis (Murdock MacQuarrie) tells people that after four such killings they need law. Hanna Lewis (Muriel Evans) bakes a cake for Milt's birthday. Tom and Minister Shaw (Allan Cavan) ask Milt to be sheriff. Milt doesn't want the job but tells Ace to stop killing. Ace shoots the lamp, and then Milt is shot in the back.
John Dawson plans to take his wagon train around the hostile Indians. The wagons roll, and people sing. A gang led by Kit (Al Bridge) attacks to rob the wagons. John asks Kit what he is doing. Kit says no guns and shoots the hand of one of his men when he pulls his gun. John loans Kit food. Kit explains how John once saved his life. Hanna greets John, but Tom tells him his father was killed. John is sworn in as sheriff and tells Ace to close the saloon at six o'clock. Ace made a deal with Norton to get rid of John, who gets a note to meet at Rainbow Falls to find out who killed Milt. John sneaks up on an ambusher named Pete and has him ride his horse; Pete is killed. John ropes horse-riders and escapes on his horse.
After six John goes to the saloon to arrest Ace. The bartender clubs John; but Ace has his gun shot out of his hand by Kit. John is carried to the church. Ace sends for Norton and his men. John revives and asks Kit and his men to be deputies. They approach Ace's men, and Ace starts shooting. Tom sets fire to the saloon but is shot. Norton's men arrive with torches and ride toward Kit's men. The saloon and other buildings are burning. Kit shoots Ace before he can shoot John; but then Kit is shot too. Before he dies, Kit asks John to take off his boots. In the final scene John puts his arm around Hanna, as the minister prays for a better future.
This basic story of a good man becoming sheriff of a lawless town to kill murderers would be repeated many times, because the violent conflict entertains while bringing across the theme of law and order.