In 1928, after Ran Farrell and his partner, Jim Andrews, strike gold in the "Lucky Jim" Mine, Farrell blows up the mine, intentionally killing Jim. Jim's dying request is that Farrell make sure that his daughter Joan receive her share of their profits. Farrell agrees to locate Grass Valley attorney Jason Howley, with whom Jim has entrusted his share of the gold they have so far mined, and buries Jim, taking his good luck charm: a silver dollar. The mine's vein soon dries up, and Farrell, who has followed the advice of a corrupt attorney named Mort Oakley, loses most of Joan's $50,000. Sixteen years later, Joan returns to claim her money, and Farrell becomes desperate. When Farrell learns that cowboy Roy Rogers plans to ship a herd of cattle by train, he and Mort organize a gang of rustlers to steal it. The next day, Farrell's men are hired to load the cattle onto trucks, and the train departs. On the way, the conductor is murdered, and the train is robbed of its cargo without ever stopping. Police Sgt. "Cookie" Bullfincher deputizes Roy, and they go undercover, dressing as hoboes. At the train tracks, one hobo admits that he was on the train at the time of the robbery, but could not figure out how the cattle were removed. Later, Cookie and Roy break into Joan's trailer, and she and her friend, Toni Bordon, mistake them for burglars. Panicked, they lock the door and drive straight to the police station. After they realize their mistake, Joan asks Roy to find out where her father is buried. Joan then goes to Farrell, but he says he does not have her money. When a telegram reports that there is no record of Jim's death, Cookie checks the local banks for recent, large deposits. That night, Farrell locks Joan inside her trailer and siphons cooking gas inside, but Roy soon arrives and rescues her before she suffocates. Frustrated, Farrell comes out of his hiding place and attacks Roy. Meanwhile, at police headquarters, Cookie learns that Howley recently received a $20,000 money order from Reno. When Roy returns to Joan's trailer to deliver the telegram, he says that the rest of the cattle will be shipped the following day. The next morning, Howley returns to the jail, claiming that Farrell is really Jim Andrews and changed his name after being released from the penitentiary. When Howley produces documentation substantiating the claim, Roy is forced to release Farrell from jail. Later, Mort follows Joan and Roy to the mine, where Joan finds her father's coat among the debris. At Howley's office, Joan then demands her money, but they tie her up and place her in the next room. Roy slips into the room through the window, and for the benefit of the gang next door, pretends with Joan that he has been murdered. Farrell then murders Howley, and Roy goes to Devil's Pass to board the train. Further down the tracks, Roy sees the robbery taking place and comes to the rescue. After Farrell shoots Mort and escapes in one of the trucks, Roy follows. Roy sees Farrell fall from a cliff to his death below and gives Joan the lucky silver dollar that belonged to her father.