Banty Bishop, the elderly foreman at the Circle K Ranch, rides into the town of Mesa on a wagon to pick up Bob Kittredge, son of the recently deceased owner Sam. Bob has been living out east and is coming to Mesa to take over the ranch. However, three outlaws ride up to Banty and force him to town over the ranch's payroll.
Bob arrives in Mesa by stagecoach along with a fellow passenger, Red Devers. Devers has been chatting to Bob about the ranch and suggests that Bob might hire him as a foreman. However, Bob tells him that he already has Banty. Banty comes riding up and tells Bob that outlaws took the ranch payroll from him. However, two men, Jake and Sandy, step forward and tell Bob that they saw Banty burying a box at the ranch. Bob doesn't believe it but Devers steps forward and suggests that they check it out so they can give Banty a chance to prove his innocence. When they go out, they find the chest and Devers points out that the only story that makes sense is that Banty "robbed" himself and hid the chest. Bob reluctantly agrees not to press charges but tells Banty that he's fired. Banty says that Bob's father would have figured the whole thing for a trigger but agrees to go peacefully, and Bob offers the job of foreman to Devers.
Later, the Lone Ranger and Tonto ride past Mesa and see a sign announcing the sale of the Circle K. Devers has authorized the sale and the two heroes know Devers by reputation. He's used different names in the past but always runs a scheme to get control of a ranch and then sell it off from under the owner a few weeks ago. The two men have heard about Bob and know he's a tenderfoot, and they figure that Devers knows about it as well. They tear down the sign and ride to the ranch to investigate.
As the two men approach the ranch, they hear a drunken Banty singing beneath a tree. The Ranger approaches him and Banty admits that he's washed up and has nothing to steal. The Ranger assures him that he's not an outlaw and the old timer invites them to make camp. As they cook up some food, Banty tells them what happened and the Ranger tells him that Devers has pulled the same kind of scheme before. Devers has fired all of the old timers that worked at the ranch and put his own men in place, and now he doesn't let anyone near the place. Despite Bob firing him, Banty doesn't want to see anything bad happen to his former boss' son. He figures that Bob wouldn't sell and is surprised when Tonto shows him the sign they found.
Tonto and the Ranger make the Ranger up as an old man and the Indian goes into town to get a wagon and different clothing. Once he returns, the Ranger rides to the Circle K and tells Devers that he's representing a secret buyer who wants to purchase the ranch. Devers is eager to sell but the Ranger wants to get confirmation from Bob. Devers reluctantly agrees, claiming that Bob had an accident and fell down. The crooked foreman goes into the next room and tells a bruised and bloody Bob to play along or he'll suffer worse than he already has. Devers then brings Bob out and he tells the Ranger that he's eager to get rid of the ranch. After Devers' men Jake and Sandy take Bob out, the Ranger says that his boss will bring the money in person in four days. To keep his identity a secret, the "boss" will wear a mask. Devers, eager to sell, says that will be fine.
After removing his disguise, the Ranger meets with Tonto and Banty and tells them what happened. He figures that Devers has to keep Bob alive long enough to sign the bill of sale, so they have four days to get help to deal with Devers' men. Banty warns them that everyone in Mesa is scared of Devers but the Ranger asks if the old timers who worked at the Circle K are willing to fight. Banty assures them that his friends will fight for Bob and that he can put together a legion of them. As Banty rides off to gather them, Tonto warns his friend that the old timers are no match for Devers' men. The Ranger figures that they'll have to come up with a way to even the odds.
Banty puts together a legion of old timers to fight for Bob and brings them back. The Ranger tells Banty and the others to give him and Tonto a ten-minute head start and then come in after them. The two heroes then ride to the ranch. Jake and Sandy, expecting a masked man, usher the Ranger into the house while Tonto waits outside with them. Devers brings out Bob and tells him to sign the bill of sale, and the Ranger jumps Devers. The two of them fight and Devers manages to fire a shot. Outside, Tonto draws on Jake and Sandy and tells them to put down their guns and sit.
The Ranger quickly subdues Devers and Bob picks up his tormentor's gun. Devers boasts that they'll never get out since his men must have heard the gunshot. Outside, Devers' thugs open fire and Tonto is forced to duck into the house. As he and the Ranger return fire, the old timers ride up to the ranch and open fire. Devers figures that his men can handle a bunch of has-beens, but the Ranger and Tonto shoot the guns out of the outlaws' hands. The old timers are still outmatched so the Ranger and Tonto decide to secretly help them, knocking out men from behind so that Banty and his friends don't realize that they're getting help.
With the two heroes' secret help, the old timers prove triumphant and tie up Devers and his men. Bob assures Banty that he won't be selling the ranch and offers them a reward. However, Banty and the others are grateful just to have the chance to work. Bob is glad to let them work at the ranch as long as they want and turns to make the same offer to the Ranger and Tonto. The two heroes are already riding off over the horizon and Banty explains to the tenderfoot that the masked man was... the Lone Ranger.