Private detective James Barlow (Randolph Scott) is sent to Indiana to infiltrate the ranks of the four Reno Brothers (Denver Pyle, Forrest Tucker, J. Carrol Naish, Myron Healy), a gang running roughshod over luckless locals. After attracting the Renos' attention with a staged train robbery, Barlow gets in deeper when he strikes up a romance with their sister, Laura (Mala Powers). Gradually, Barlow devises a strategy to set the brothers up for ambush in another train robbery.