Thunder Over the Plains.

Set in 1869, after the Civil War, Texas had not yet been readmitted to the Union and carpetbaggers, hiding behind the legal protection of the Union Army of occupation, had taken over the state. Federal Captain Porter, a Texan, has to carry out orders against his own people. He brings in the rebel leader Ben Westman whom he knows is innocent of a murder that he is accused of. In trying to prove his innocence, Porter himself becomes a wanted man.