Red Devers and his gang have been victimizing ranchers for profit, and their next victim is Bob Kittredge ( DeForest Kelley), who's returned from the east to take over his late father's ranch, the Circle K. Now that the entire gang is in jail, the Ranger decides to keep wearing his mask and fighting criminals. The next day, Cavendish and the rest of his gang ride to Colby, fully expecting to take over the town, but find the heroes and a posse blocking their way during the fight, the Ranger chases and catches Cavendish. The Ranger has a plan: with the doctor's help, they quietly round up all the men who had replaced the murdered officials. Acting alone, the two heroes go back and rescue the sheriff and the town doctor (who had patched up Cavendish's bullet wound) from Cavendish. The Lone Ranger and Tonto try to get help, but the sheriff's men are in cahoots with Cavendish. With the help of Blane and the sheriff, the Ranger and Tonto capture Cavendish and some of his men, but then the rest of the criminal gang arrives. Riding on Silver and Scout, the two men travel to Colby to visit the Ranger's friend Jim Blane, who owns a hidden silver mine however, they find that Cavendish and his men have been killing and replacing key people in the town in order to take it over, and planning to frame Blane for the murders.
They nurse the horse back to health, and the Ranger slowly gains the animal's trust and names him Silver. Later, while looking for a horse for the Lone Ranger, he and Tonto find an injured white stallion, whom they rescue from an enraged buffalo.
Preparing to hurl a rock at the Ranger, Collins loses his balance and falls to his death. Suddenly, Collins-who had also survived being shot-attacks from the top of a nearby cliff, because he wants Tonto's horse, Scout. Tonto nurses him back to health, and the Ranger decides to let everyone believe that he's dead a sixth grave is made next to the graves of the other five Rangers, and the man puts on a mask. Hours later, the Indian Tonto comes along and finds that one of the Rangers, a childhood friend of his, is still alive. In the old west, six Texas Rangers are led into an ambush by their treacherous guide, Collins Butch Cavendish and his gang of outlaws shoot all the Rangers, and then Collins, and leave them for dead.