Maverick - Season 4 Episode 5 : Last Wire from Stop Gap 1962

On their way to Denver, Beau and Bart Maverick pick up $6,500 in a poker game at Stop Gap. They decide to wire the money to Denver through the Hulett Telegraph Company. They discover the company is a fake and that the telegraph line leads to a cave two miles away where the crooks stash the customers' money and send phony messages in return. The cousins devise a scheme to recover the money and put the company out of business.