Rim of the Canyon (movie, 1949)

20 years ago, 3 men robbed a stage and hid $30,000. They were caught and sent to prison by Marshal Steve Autry (Also played by Gene Autry). 20 years later, the men bust out of prison and return to the ghost town where they stashed their treasure searching. Steve's grandson picks up where Steve left off to foil the plans of the outlaws.