Pacific pearl diver Duke Slade escapes angry natives by joining a whaler whose dying captain persuades him to marry his daughter who is already being wooed by the first mate.

Slick gambler James Wylie is apprehended by the law and given the option to forgo a prison sentence if he poses as a bandit. His mission is to uncover the identity of the Poet, a notorious outlaw who has been holding up bank-owned stagecoaches and leaving verses at the crime scenes to taunt the authorities. James finds time to woo the Poet's lovely wife, Ann, who initially cold-shoulders him. But, as a romance develops, they partner up to find the robber.

Hoppy and Lucky have been called in to investigate a series of stage holdups. The robbers are taking gold from Colby's mine and Hoppy suspects it may be ex-outlaw Colby himself. When Speedy strikes gold, Hoppy borrows it and announces a gold shipment hoping to catch the gang and their leader.

European bad guy Baron Bendor leads some local townsmen in a plot to obtain horses through theft. Hoppy and his sidekicks Lucky and Speedy must find and expose the horse thieves.

Buck Colins heads a group of local ranchers who are trying to prevent the railroad from completing its line through their property. Till now they have been able to charge tolls on herds passing through. Hoppy goes undercover to expose them.

U.S. Marshal Hopalong Cassidy is called when a town becomes overun with bad guys. Disguised as a member of a medicine show, Hoppy discovers that the ringleader is none other than sweet li'l ol' Ma Burton.

A dedicated FBI agent recalls the agency's battles against the Klan, organized crime and Communist spies.

Two young men set out on a fishing trip. They run into a gang of criminals who are menacing two young women.

Slightly more elaborate than most Charles Starrett westerns, Down Rio Grande Way is set in the mid-19th century, when the Republic of Texas was poised to join the Union. Starrett plays Texas Ranger Steve Martin, who is dispatched to a "renegade" Texas country that refuses to become part of the good old USA. He discovers that the crux of the problem is a local tax collector who, with the help of a crooked newspaper editor, is systematically robbing the citizens of their hard-earned cash, all the while fomenting anti-American sentiments.

Hoppy is busy chasing stagecoach bandits who sing as they rob.