Rhythm of the Rio Grande.

Tex and Shorty ride into Cinco Valley, a gold rich area terrorized by marauders ostensibly lead by one Pablo. Tex, however, recognizes Blackie, whose boss is Bannister, an American. Suspecting that Bannister and his henchmen are trying to drive the settlers off their potentially valuable land by posing as Mexican banditos, Tex convinces Pablo to help him set a trap for the marauders.