A man from Laramie comes to Apache country where his brother was killed, and he meets the niece of a rancher, his son, and his foreman with complicated relationships.
Will Lockhart (James Stewart) stops his wagon and says they will camp there. He looks at the burned remains of a wagon and finds a black hat. Charlie O’Leary (Wallace Ford) says hate is unbecoming in a man like him. They drive into town. Will brings supplies to the store and finds that Barbara Waggoman (Cathy O’Donnell) is in charge. She says she has wanted to go back east since her father died. She gives him tea. Will says he came from Laramie, but he has no home. He sees a repeating rifle and asks where it came from. An Indian tells him that an Indian traded it.
In the evening Will sees Barbara on the street and asks her where he can get a load of freight. She suggests there are salt lagoons near Apache land. She advises him to avoid Indian trouble and head back to Laramie.
Will, Charlie, and some men are digging salt. Ten men arrive on horses, and Dave Waggoman (Alex Nichol) accuses him of stealing the salt. Will offers to pay for it, but Dave has a man lasso Will and has his wagons burned. Then he shoots their mules. Vic Hansbro (Arthur Kennedy) arrives and stops him from killing the mules. He tells them to get back to the ranch. Vic gives Will his gun back, and he advises him not to start any more trouble. Will pays off his men, and they leave. Charlie says he going to the Apaches to see if he can get some information because he likes Will.
Will rides back to town and asks Barbara who owns the salt lagoons. She says Dave is her cousin and that Alec Waggoman is the man. Will says he likes to watch her because she is beautiful.
Dave and his men bring cattle to town, and Will sees him. Will pulls him off his horse and slugs him several times. Vic intervenes, and they fight. Kate Canady (Aline MacMahon) holds a rifle on Dave while they fight. Alec Waggoman (Donald Crisp) arrives and tells Vic to stop. Will complains he had twelve mules killed and his wagons burned. Alec offers to pay for them and advises him to leave. Will thanks Kate, and she offers to take him in her buggy to her ranch. He gets in, and Chris Boldt (Jack Elam) warns Will not to go with her because the Waggomans won’t like it. Vic and Barbara discuss the situation, and she says they should leave. He kisses her and says he wants to stay at the Barb.
Kate hires Will to be her foreman. He declines, and she asks why he is there. He says his brother is dead, and that is why he came. She offers him supper.
Will rides a horse to the Barb ranch, and Vic shakes his hand. Alec offers Will $600 for his losses. Will notes that Alec does not have trouble with the Apaches. Will says Apaches killed twelve cavalry on his land. Alec says he wants to be friends and have Will work for him. Alec says he was expecting him. Alec gets the money from his safe and pays Will, who notes that Alec does not see well. Vic advises Will to go elsewhere. Will rides off, and Alec tells Vic the $600 comes out of his pay. Vic says Dave did it, but Alex says Vic is responsible for Dave. Alec warns Vic he may fire him. Vic objects and dares Alec to fire him. Alec says he only cares about Dave.
Will meets up with Charlie, who advises him to go back to Laramie. Charlie says the Apaches have repeating rifles and are expecting to get more soon. They see a man on a horse, and Will with a rifle asks why he is following him. Chris says he is earning money, and he offers information for money. Will asks who he is working for. Chris asks permission to leave, and Will warns him not to follow him again.
In town Sheriff Tom Quigby (James Millican) urges Will to leave town. Will declines, and Tom advises him to pay the undertaker in advance. Later Chris jumps Will and tries to kill him with a knife. Will throws him off, and Chris runs away. Will follows Pueblos into the church. He sees Barbara, and the priest says it is a wedding. They talk about the Apaches and the rifles. Will tells Barbara and Vic that he is staying. Vic and Barbara are getting married. Will goes out, and Tom asks for his gun. He asks about Chris, and Will says what happened and that the Indian there saw it. Tom says Chris was knifed to death, and he arrests Will.
Alec visits Will in jail and says he does not interfere with Tom; but he will get him a friendly judge and a lawyer. Alec asks Will if he dreams. Alec says he keeps dreaming about a stranger coming into his home like Will. Alec says he comes with a gun to kill his son Dave. Will still refuses to leave the area. Outside Kate says hello to Alec. Kate visits Will and gets him released into her custody. He reluctantly accepts.
Alec asks Dave to check the figures on the beef, but Dave says he is not good at that. Dave tells his father he will try to please him, but he does not like Vic giving the orders. Vic comes in and says Kate got Will out. They start to go, and Alec tells them to stay away from the Half Moon. Alec gives Dave his orders and warns him he will not let him fritter away what he built. Alec tells Vic he is going blind, and Dave overhears. Alec tells Vic to think and take care of his son, and he will love Vic.
Kate instructs Will what to do with the cattle. Dave and Alec find Half Moon cattle on their ranch. Dave says he heard what Alec said. Vic says he is in command. Vic says he and Ned will handle those cattle, and he sends Dave and the others to handle their own cattle. Dave sees Will riding and shoots at him. Will takes cover, and they shoot at each other. Will shoots Dave’s right hand. Dave and his men ask Will why he is on Barb land. Will says he is checking Half Moon stock. Dave has his men hold Will, and he shoots his right hand. Dave says he is riding to town. Dave’s men help Will on to his horse. Vic follows Dave up a mountain. Dave uncovers a loaded wagon and opens a box of rifles. He gathers wood, starts a fire, and uses a blanket to send smoke signals. Vic arrives and tells him to put out the fire. Vic warns him that the Apaches will use the rifles to kill them all. Dave holds a gun on Vic with his left hand. Vic tries to reason with him and says he will tell his father. Dave says what he will do. Vic says he is crazy and makes him drop the gun.
Kate treats Will’s hand and tells Barbara how Alec’s wife spoiled their son Dave. Will thanks Kate for doing as good a job as an Army surgeon. Barbara tells Will he has made her unsure about how she feels. She starts to go, and he asks her to stay. She talks about Daniel Boone and then runs out.
Vic brings Dave back unconscious and over a horse. Alec feels his head. Dave’s men say that Will must have done it, but Vic says that Alec will decide.
Tom calls on Kate and Will, and he says Dave is dead. Will says he did not kill him. Tom says he just came to warn him.
Alec and the others attend the funeral. Kate tells Alec she feels sorry. Vic tells Alec he will go with him, but Alec orders them all to stay in town and leaves. Alec rides toward Will, who tells him to stop. Alec shoots blindly and is thrown from his horse. Will says he has not found the man he came to kill and that he is not the man in Alec’s dream. Alec gets on his horse and rides off.
Alec asks Vic about the bill for French wire and asks what was in the wagon. Alec asks if Dave sold guns to the Apaches. Alec says they have to find the wagon. Vic asks why, and Alec says he has to know.
Will finds Charlie, who says he saw the tracks of one wagon. Will suggests they pick up the trail. Alec tells Vic they should try the mountain. Vic discourages him but follows. Vic admits he found Dave’s body near the wagon of guns. Vic says he loves Alec and asks him not to go. They struggle. Alec falls off his horse and rolls off a cliff. Will and Charlie check the creek where the wagon tracks end. Will finds Alec on the mountain.
A doctor tells Kate and Will that Alec is still unconscious and that he is blind. Will says somebody pushed him. Barbara asks Will to tell her who it is. He asks why she is afraid. Vic comes in and asks how Alec died. Will says he is unconscious and should not be disturbed. Will asks Vic who would have wanted to get rid of Alec. Vic says he made many enemies. Later Kate says he is asking for Will. He goes in, and Alec says he found out about the rifle shipment. Alec says Vic killed Dave and tried to kill him and that is the man Will is looking for. Will goes out and rides off. Alec asks Kate to stay with him, and she says she never left him.
Will gallops and goes up the mountain. He sees a man sending smoking signals; it is Vic. A band of Apaches sees the smoke and ride their horses. Will holds a rifle on Vic and says he came to kill him. Vic says he has no cause. Will says his brother and the cavalry were massacred by the Apaches. Vic sees the Apaches coming and warns Will, who makes Vic help him push the wagon off the cliff. As it falls, the ammunition explodes. Will tells Vic to get away from him. Vic rides off and is surrounded by the Apaches who kill him.
Will asks Kate when the wedding is, and she is glad that Alec needs her. Will says goodbye to Barbara and says she could find Captain Lockhart in Laramie.
This carefully crafted western lets the audience identify with the hero who manages to get revenge without killing anyone. The surprise ending is arranged by making the villain appear to be the reasonable man who is restraining the immature and violent son. The audience assumes that the crazy man is the problem, but the selling of weapons to those who use them to kill people is often done by reasonable people who are pursuing their own selfish goals. The white characters are well defined, but the Apaches only represent dangerous violence.