As he drives a stagecoach carrying a million dollars to the town of El Dorado near the Powder River, Nugget Clark is attacked by bandits. Allan "Rocky" Lane, who works for the Northwest Railroad Company, which is planning to lay tracks in El Dorado, sees the runaway coach and stops it before the outlaws can claim the money. Later, Nugget goes to the Statton Hotel and reports the attempted hijacking to "Shears" Williams, the sheriff and town tailor, and his friend, hotel owner Lucius Statton. When Nugget produces Rocky as a witness, Statton, who is trying to hoodwink the town and wants to kill Louise and Bob, who may expose him, says that Bob Manning, one of his employees, was probably behind the attack. Just then, a man claiming to be Bob walks in and introduces himself as a representative of the Northwest Railroad, which he says may not build in El Dorado because bridging the Powder River would cost $100,000. Bob adds that his company would agree to fund half the cost, if the residents could provide the balance within three days. Rocky then goes to Nugget's place, and is shot at by Statton's henchman Devereaux, who also claims to be Bob Manning. Later, Rocky meets Williams' boss, "Bull" Macons, and shows Nugget the letter that the real Bob Manning had sent asking him to come to El Dorado to meet his new bride, Louise. After Nugget tells Rocky that Louise sent a telegram to announce her eminent arrival on the overland stage, Rocky cuts into the wires with his pocket knife and, using Morse Code, sends a message stating that Louise's plans for arrival have been changed. The telegraph operator then delivers the message to "Mr. Manning" at the tailor shop. Meanwhile, Rocky and Nugget ride out to meet Louise's stage to tell her that her life may be in danger. After Rocky places a dummy resembling Louise inside the stage and begins driving, the bandits attack. Just as Nugget and Statton report that the bandits have murdered Louise, Rocky receives a telegram announcing that the real Bob is being held captive. Later, Rocky sends a telegram asking the kidnappers to meet him at Junction Point, then leaves. After Williams throws a knife into Statton's back, he orders his men to go to Junction Point, where they try to frame Rocky for Statton's murder. Williams sends Bull and the posse after Rocky, but he escapes on his horse Black Jack. After Louise insists that Rocky is innocent, they take her prisoner. Rocky goes to see Williams at the hotel, where Devereaux says that he fears for his life. Before Devereaux can tell him where Louise is being held, Williams throws a knife into his back. Rocky stops Bull from shooting Bob and arrests the gang. When the bandits realize that all of Rocky's "men" are dummies, however, they escape. Williams tries to steal a saddle bag full of money, but Rocky shoots him. Rocky struggles with Bull, while Nugget kills Williams. After Bob is reunited with his wife, Rocky bids them all farewell.