In the 1840s, Ramsey MacKay, the driver for the struggling Wells Fargo mail and freight company, will secure an important contract if he delivers fresh oysters to Buffalo from New York City. When he rescues Justine Pryor and her mother, who are stranded in a broken wagon on his route, he doesn't let them slow him down and gives the ladies an exhilirating ride into Buffalo. He arrives in time to obtain the contract and is then sent by company president Henry Wells to St. Louis to establish a branch office.

Montana and sidekick Pancho hire on at the Lopez rancho to fight Daggett and his outlaw gang. But Lopez's foreman Barnes is one of Daggett's men and he frames Montana for murder.

Ken Maynard's exceptionally intelligent horse, Tarzan the Wonder Horse, is the star of this western about evil cowboy Steve Frazer (Welch) who gathers horses for slaughter, whose meat is sold to pet food manufacturers. The wild horse Tarzan frees the doomed horses from their corrals, and Frazer convinces the Sheriff that Tarzan is a threat and can be shot on sight. Local cowboy Ken Benson (Maynard) and rancher Pat Riley (Kennedy) work together to clear Tarzan's good name and put Frazier behind bars for his evil deeds.

Seeker Dean has found the gold he has been looking for for 15 years. Heading for the Government office, Boone Jackson kills him. Kickabout finds a cryptogram as to the gold's location and Sergeant Kinkaid solves the puzzle. But Jackson learns of the gold's location and to get it, he sets out to dynamite the dam that would flood the entire communuty.