Clint Travis goes undercover as a gun smuggler to stop Mexican revolutionary Juan Morales' plans to topple the Mexican government.

The Rangers set out to stop a smuggling ring that's bringing Chinese immigrants across the Colorado River.

Arizona's territorial governor orders Rynning to investigate reports of abuses by prison guards of convicts working on chain gangs.

Ben Haddock, a recently hired trail boss, is fired by Red Emerson for dating his daughter. The two men have an argument over the money owed to the foreman resulting in the Ben shooting Red and taking the money he feels he is owed. Travis rides out to arrest Haddock but is stung by a scorpion and cowhand flees leaving the ranger to die.

When a gang of American outlaws takes over a Mexican border town, Colonel Kesterlitzky aka 'El Tigre' of the Mexican Rurales requests the assistance of Captain Rynning to recapture the town.