With fences cut and livestock disappearing, Jeff Browning suspects his new neighbor, Dan Murdock. Sheriff Fletcher appeals to the U.S. Marshal for help, and Tom Murdock, Dan's son, is sent. Tom arrives in Buffalo Springs, posing as cattle buyer Tom Morgan, with the Sons of the Pioneers as his foreman and ranch hands. Browning's foreman, Bat Springer, is alarmed at the news of the impending sale of the Browning herd. He and Murdock's foreman, Carver, have been rustling cattle from both ranches, changing the brands and loading them into railroad cattle cars at a distant siding. Dan discovers that the brands from both ranches have been changed to the Bar-X, a brand that is registered to Browning's son Ned. As he is telling this to Browning, he is killed from ambush and Browning is knocked unconscious. But Tom has seen Bat steal Browning's unfired gun, the only clue to Browning's innocence, and tells his suspicions to Ned and his sister Jean.