Synopsis: The Three Mesquiteers -- Stony Brooke, Tucson Smith and Lullaby Joslin -- suspect the unscrupulous Rance McGowan of supplementing his income by rustling a breed of wild horses protected by the federal government. When Sheriff Miller gets trampled to death by an unknown horse, the Mesquiteers seek vengeance for his orphaned son. Meanwhile, Brooke angers Smith by courting saloon girl Rita.