Ben Mockridge, Ben Mockridge, is a young man proud of his $4 handgun — a flashy symbol of his dream of "cowboyin'" life. He asks Frank Culpepper if he can join his cattle drive to Fort Lewis, Colorado. Culpepper, a reformed gunslinger, reluctantly agrees and sends Ben to the cook to be his "little Mary." Ben bids farewell to his mother, who tells him to be a good boy.
Ben soon discovers the adults have little patience for youngsters. Despite the warning, Culpepper assigns Ben tasks that he handles clumsily, setting up a rocky start for the greenhorn. When rustlers stampede the herd, Culpepper and his hands pursue them and kill the rustlers, even when some are disarmed, paying a heavy toll with four of their own fallen.
Culpepper leads the drive toward a box canyon, and the odds begin to tilt against them as the group confronts the economics of cattle rustling, with the rustlers demanding 50 cents a head for the roundup. The confrontation ends with a brutal show of force as Culpepper’s crew shoots their way through, leaving a trail of bodies and frustration.
On the road, Culpepper directs Ben toward a cantina a day’s ride away to find Russ Caldwell, Russ Caldwell. Before Ben can reach Caldwell, a band of trappers robs him of his horse and gun. When he finally meets Caldwell, Ben and three companions agree to join the drive, but their path intersects with the trappers again, and the group quickly asserts itself by taking the trappers’ possessions after a deadly confrontation.
That night, while Ben keeps vigil, a one-eyed horse thief distracts him and another thief ambushes him, resulting in more horse theft. Culpepper is furious at Ben’s apparent naiveté and lack of caution. The tension peaks when Ben’s failure to shoot the one-eyed intruder leads Culpepper to decide that Ben’s usefulness is limited, and he contemplates drastic measures.
A harsh decision follows: Culpepper orders Ben in a tense sequence that culminates in a high-stakes attempt to acquire horses in a saloon town. In a tense shootout, Ben earns a measure of redemption by killing the patron who lunges for a shotgun, while Culpepper’s group dispatches their opponents, with one survivor pointing Culpepper toward the horse herd.
Back with the drive, Ben crosses paths with Caldwell’s crew, and when a ranch hand refers to Caldwell disrespectfully, a gunfight is proposed to restore “honor.” The hand declines the trouble, and Culpepper, frustrated, warns Ben to keep a low profile. As they move, Culpepper rides ahead to settle matters with the landowner and pay for grazing rights so the herd can graze legally on the land.
In a town, they meet a group of religious pilgrims led by Nathaniel Green. The pilgrims invite the cattle to water in a gesture of hospitality, signaling a possible peaceful settlement. The landowner, Thorton Pierce, appears with henchmen and insists the land is his, giving Culpepper and the others a stark ultimatum: leave within an hour or face trouble. Green believes Culpepper has been sent by God to help, while Culpepper argues that Green should depart to ensure safety. With Fort Lewis within reach, Culpepper contemplates leaving to protect the drive’s future.
Ben chooses to stay, convinced he can still make a difference. He reveals that he hid his gun during the earlier barroom ambush, showing a degree of resolve. As Culpepper rides off, Caldwell and his three friends—compelled by a mixture of conscience and revenge—turn back to defend Green from Pierce, much to Culpepper’s exasperation. Yet Culpepper ultimately leaves them to press on with the cattle.
In the climactic shootout that follows, nearly all of Caldwell’s faction and Pierce’s group are killed, leaving Ben alone on the field of bloodshed. Green confronts the grim reality: the land has been stained with violence, and staying may no longer be possible. “God never intended us to stay—he was only testing us.” With those words weighing on him, Ben buries the four bodies of his fallen companions, discards his gun, and rides away into an uncertain future.
