Buckaroo Sheriff of Texas (1951)

It's just after the Civil War in Texas and Sam White has found a rich deposit of bauxite. But lawlessness abounds and Jim Tulane and his henchmen are in control. Tulane knows White has found something but is unable to find out what and kills him. He also knows the key is in a toy wagon White gave to his son. The son figures out the puzzle only to learn that Tulane's henchman has already accidently found the answer.