In Colorado, Bret, Bart, and Dandy Jim Buckley are caught in a leaky cabin when storm season strikes. As they try to stay dry, Dandy Jim says that they should have gone to Texas and enjoyed the dry weather. The Mavericks refuses and Dandy Jim asks what they have to hide. The brothers finally agree to tell their friend the story and explain that they're wanted for the murder of two men.
Bart and Bret serve as Indian fighters with the Union Army to avoid imprisonment during the Civil War. After the war ends, they return to their hometown of Little Ben, TX, for the first time in five years. Many returning Johnny Rebs are out on the streets since Union forces now control the town. The brothers go to the grocery to collect $1,650 from the owner, Jessie Hayden. They show Hayden the receipt and inform him that they left the money with his father dead father. Hayden finally pays the brothers in Confederate money and they point out that they gave his father gold. The Mavericks demand to see the ledgers and Hayden's men attack them.
After a brief fight, the Mavericks brothers dispose of their attackers but Hayden destroys the receipt and calls in the local Union lieutenant. Hayden is prepare to lie and have them arrested, but a woman steps out of the back room and says that she saw the entire thing. When the Army lieutenant arrives, Hayden reluctantly pays the $1,650 and then offers the Mavericks double that for their land. The brothers refuse and turn to the woman, only to discover that she's slipped away. The Army lieutenant tells them that the woman is Laura Miller and she and her father moved to Little Ben four years ago. The brothers find a note from Laura inviting them to her ranch. They draw cards to see which one will go and Bret win. However, when he arrives he discovers that Bart is already there. Bart quickly figured out that Bret crimped the cars to draw high card.
Laura explains that she wants to hire both brothers as trail bosses for a cattle drive. When they refuse, Laura explains that Hayden has been buying all the land in the territory. When her father died in an accident, Laura realized that Hayden was responsible. She broke into his house to shoot him but couldn't bring herself to do it. However, Laura spotted a map revealing Hayden's plans for the territory. Now she plans to raise $80,000 by taking 2,000 cows to Fort Adobe where the Army needs meat. The Mavericks warn her that the land between Little Ben and Fort Adobe is filled with Indians and short on waters, and Laura admits that everyone else has said it can't be done. She wants the Mavericks because they know the territory and offers them 10% to do the job. The Mavericks refuse, explaining that they have spent enough time fighting for others and now they plan to fight for themselves. Laura warns that only have a narrow window of opportunity but the Mavericks stand by their decision.
As Bret and Bart ride home, Jim Hazlit and Miguel ambush them on the road. Bret catches a glimpse of Miguel's boots before he's knocked out. The two men take the brothers' money and go to the ranch. Jim, Laura'a foreman, gives her the money but objects to her plan to force the brothers to work for her. He tries to kiss her and she backs away, and Jim complains that she's changed since her father died. Laura says that she'll worry about their relationship once she gets revenge for her father. When she asks if Jim is abandoning her, Jim tells her that he doesn't have the guts to do it.
Bret and Bart assume that Hayden had them ambushed but have no proof. They have no choice but to sign up with Laura and find cattle drivers. The Mavericks turn to the local Johnny Rebs and ask them to join the cattle drive. One of Hayden's men, Jett, rides up and accuses the Mavericks of having sold out Confederacy to serve with the Union Army. The brothers explain that they choose service as Indian fighters over a prison term but never fought Confederate forces. Many of the Johnny Rebs were in the same situation and the tide turns against Jett. Bret yanks Jett off the horses and challenges him to fight with guns or fists, but Jett rides away when he realizes that he's outmatched.
That night, two of Hayden's men ambush Bret and Bart as they come out of their hotel. However, a tall man in his 20s spots them and yells a warning to the brothers. They kill the ambushers and tell the sheriff what happened when he arrives. However, when they need the tall man to testify, they discover that he's slipped away.
Bart and Bret ride out to Laura's ranch the next day and she warns them that the Army lieutenant is coming to arrest them. Hayden has testified that the Mavericks shot first so they're wanted for murder. Laura tells to meet them once they cross the border, but the brothers ride back to Little Ben to find the man who can clear their name. They confirm that he's left on a wagon drain heading for the border and flip to see who will go after him. Bart loses and rides off after the tall man while Bret rides after the cattle drive and Laura.
The Army lieutenant takes a platoon of men to follow the cattle drive and find Bret. Bret has no choice but to follow them and wait until they finally give up and return to Little Ben. Meanwhile, Bart goes after the wagon train and discovers that Indians have killed most of the settlers. The tall man caped with several wagons and Bart goes after them.
As the cattle drive camps for the night, Bret spots Miguel and recognizes his boots from the ambush. He demands his money back and Laura admits that she set up the brothers. When Jim tries to intervene, Bret knocks him down and goes into the tent with Laura to demand the money back. She gives it back to him and begs him to stay. Bret agrees for 25% and Laura has no choice but to accept his new offer. Bart rides up and tells them that he's spotted Hayden bringing his own herd of 2,000 cows to Fort Adobe. He's also confirmed that the tall man and the surviving wagons are heading for Fort Adobe as well.
The brothers drive the herd at top speed and get within two days of the fort before taking a break. Hayden visits the camp and talks to Bret privately. He explains that he's filed a deposition with the lieutenant but will recant it if Bret and Bart sabotage Laura's cattle drive. Bret refuses and Hayden insists that he's doing the right thing. If he doesn't buy the land, a Union carpetbagger will. Hayden is the only one with the money to control the land and keep the Union out. Unimpressed, Bret tells him to leave and figures that Hayden will try to stop them by stampeding the herd.
Bret, Jim, and Miguel take some of the men and ride off after Hayden. They spot Hayden and his men riding toward Laura's herd and lure them into an ambush. As the two sides shoot it out, Bret tries to get above Hayden and take him out. Hayden spots him but Jim shoots him. Bret tells Jett and the others to surrender now that their boss is out of the picture and they quickly flee. Jim confirms that Hayden is still alive and the businessman agrees to tell the truth about the murders if Bret gets him treatment.
At Fort Adobe, the doctor tells Bret that Hayden is going to die. Bret calls the doctor in as a witness and asks Hayden to tell the truth. As he dies, the businessman just smiles and tells Bret to hang.
Laura turns in the cattle for $80,000 and suggests that the Mavericks come back to Little Ben. She believes that the authorities will drop the charges, knowing that Hayden hated the brothers. Bret and Bart disagree and figure they'll be better off finding the tall man and clearing their names. Bret salutes Laura, who kisses him in return before riding off with Jim.
As the Mavericks finish their story, Dandy Jim asks if they ever plan to go back to Texas and settle down once they find the tall man. The brothers are clearly less than thrilled at the idea of settling and admit they're in no hurry to find their witness. As the cabin drifts off in the flood, Dandy Jim promises not to notice the tall man if he ever sees him.