A mysterious outlaw known as Pegleg dreams of an empire in the vast, rich wilderness west of the Mississippi River. Army Lieurenant David Brent (Richard Fiske) is sent from Washington to persuade Kit Carson (Bill Elliott) to put an end to the reign of terror caused by Pegleg's gang called the Black Raiders. Carson agrees and, in the course of his assignment, he meets and is attracted to Caremelita Gonzales (Iris Meredith), the adopted daughter of a Spanish grandee, Don Jose Gonzales (Frrancisco Moran), who is heading west via a wagon train. Escaping an avalanche started by Perleg's henchmen, Kit captures Natchez (Dick Botiller), a Black Raider, and just as he is about to reveal the real identity of his boss, he is slain by Pegleg. As he seeks the killer, Kit narrowly escapes an Indian ambush and rides to warn the trappers and citizens at Stewart's Post that Pegleg intends to massacre them.