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.

Julie Bronson, whose father operates a desert cafe, is attracting the unwanted attention of a half-crazed gangster known as The Ghost who runs a desert night club several miles away.