The Maverick brothers are riding on a stagecoach which gets held up by Mr. Rumsey Plumb, a road agent who demands respect. When Bret and Bart want to know what's going on, the driver introduces them as the new owners of the stage line. Rumsey isn't too thrilled to learn that they are broke but he's really upset when they profess to have no interest in the stage line which they inherited. With nothing to rob, Rumsey is concerned: "How am I gonna send my poor old mother snuff money," he asks?
In town, Bret and Bart are informing the attorney, Atherton Flayger, that they aren't interested in the stage line when Polly Goodin walks in and offers to buy it. Once they learn that they have to pay her $2,000 a year for access rights just to stay in business, they are even more interested in selling. Although Miss Goodin has no money, she offers them each $1,000 a month for life. Mr. Flayger says they can't sell because their Uncle Micah wanted them to work the line, not to become more idle and shiftless than they already were. However, after Miss Goodin leaves, Bret discovers that the superfine print says that the stage line can be sold for a substantial profit. They tell Flayger to prepare a bill of sale and set out to find Miss Goodin. An obviously displeased Flayger has his clerk read him the ultra-fine microscopic print which says that the stage line reverts to him, as executor, should disaster befall the Mavericks. He has his clerk seek out Shotgun Sparks, the local hired gun. Meanwhile, Shotgun is meeting with Miss Goodin, who wants him to blow-up the stage without hurting those nice new owners.
Just after Sparks convinces the Mavericks to let him drive them to Miss Goodin's ranch, Flayger comes up and hires him to kill the both of them. Out on the road, Shotgun stops the stage for lunch and fetches his dynamite. As Bret and Bart begin to eat, he plants a bomb on the stage and lights the fuse. Bart smells the burning fuse, finds the bomb and throws it away just before it blows. Then Sparks points a shotgun at the Mavericks and orders them to raise their hands. He refuses to tell them who wants them dead. But before he can shoot, Rumsey Plumb comes up behind him and orders him to put his hands up. Rumsey's not happy when he learns that Shotgun was trying to blow up the stage, which would put him out of business. He orders Sparks to hightail it out of there and tells the Mavericks to just have that gold dust shipment on the stage later.
Shotgun rushes on to Goodin's ranch and tells her that the stage is coming and that he's still going to blow it up on the road south. When the Mavericks arrive they agree to sell the line and prepare to head back north to town to sign legal papers with Polly. While all three are in the ranch house, Shotgun puts a timed bomb in the stage's lock-box. On the way into town, the stage is held up again by Rumsey Plumb. He doesn't believe that they haven't been back to town yet and orders them to hand down the lock-box. As they drive away, Rumsey shoots at the box and it blows up. The Mavericks and Miss Goodin rush back to help. "You know, Maverick," says Rumsey, "I've been shootin' the locks off of express boxes for 20 years. That's the first one ever shot back at me." Polly rides on into town with Bart, leaving Bret to watch over the dazed Rumsey Plumb.
Back in town, Flayger is gleefully finishing up legal paperwork setting up the Flayger Transportation Co. He is surprised when Bart and Polly walk in, undead. He tries to stall the sale by demanding documents, but Polly just happens to have them with her. After the two go to dinner, expecting Flayger to write up the bill of sale while they're gone, Shotgun shows up looking for the $100 balance due on his contract for killing the Mavericks. He refuses to believe that they're not dead. Flayger's clerk then runs in shouting that he's found a huge loophole which the lawyer can exploit. When Polly and Bart return, Sparks still can't believe it. He pulls a gun on Bart after Bart suggests that they should go see the sheriff. Flayger enters and tells Polly that, legally, her ranch does not exist because her land grant fails to define the boundaries of the property. Therefore, the land is public and there can be no right-of-way sale. He also informs her that her ranch is up for grabs in tomorrow's big land rush. Bart says that they should hire the fastest horses around and stake out the ranch before anyone else can. But Flayger hires Sparks to use his (Flayger's) thoroughbred to get to the ranch first and claim it for him. He also tells Sparks not to mess around with any more dynamite - if the Mavericks get in the way, just shoot them.
Polly and Bart discover that there isn't a saddle horse to be had anywhere. They'll have to use the stagecoach horses. Bart is not confident: "You know, if Paul Revere rode any one of those bangtails, we'd be walking around today in red coats." The next day the old horses will barely move. Once the race begins, Sparks quickly takes the lead, with a large crowd trailing a ways behind him. He passes by Bret and Rumsey Plumb. Then, way behind, Bart and Polly ride up. Rumsey loans Bret his horse and Bret takes the marker stakes from Bart and rides off. He catches and passes Sparks, who falls off his horse when he fires his shotgun. Bret gets to the ranch and drives Polly's first stake into the ground and then races off to place another. Sparks rides up and pulls out the marker, replacing it with one of Flayger's. When Bret begins to hammer another stake in, Shotgun shoots at him. Eventually, after several near misses, Bret knocks Sparks out and all is well.
But then, at her now secured ranch, Polly introduces the smiling Mavericks to Mr. Cox, an attorney. He produces documents that the two brothers sign willingly, dreaming of all those $1,000 checks that will be coming their way for the rest of their lives. However, as soon as the Mavericks depart, Polly signs the right-of-way over to Mr. Cox for $10,000 cash. Bret and Bart are out sharing a campfire meal of fresh quail with Rumsey Plumb when Mr. Cox stops by on his way back into town. He informs the stunned Mavericks that he has acquired the right-of-way for the Far Western Railroad and leaves them with an apologetic note from Miss Goodin. The clang of hammers from a nearby railway camp signals the finality of their situation. However, despite losing his stage robbing career, Rumsey is overjoyed: "I dreamed of this all my life. Do you know how much gold dust they carry in one railroad express car?"