When the cattle barons of the Rockies wanted to eliminate homesteaders encroaching on their grazing land, Tom Horn was their deadly solution. Trained as a scout and sharpshooter during the bloody Apache Wars with Geronimo in the 1880s, Horn was as skilled a man hunter as they came. But he was also a heartless killer who took a psychopathic pleasure in watching men die. He would leave one warning, and if it wasn't heeded, he would shoot to kill, never leaving a trace. Horn was the most effective assassin in the business until ultimately, his twin weaknesses - pride and alcohol, put him in the crosshairs of the law. Featured interviewee: Paul Hutton, renowned Western historian, commentator and film consultant.