After the brutal murder of his uncle, U.S. Marshal Bob Stevens sets off on the trail of the killer. A knife is the solitary clue left behind at the murder scene. Stevens knows that the murderer has accomplices, and decides to pose as a crook himself to attract the attention of his gang. After joining the violent band of stagecoach thieves, Stevens must face the task of unmasking their leader while dodging the local sheriff.
Bob Steele, who dominates Marked Trails with his usual straight-edged, no-nonsense character, meets his match in Veda Ann Borg, a hard-boiled femme fatale with a cold heart and fierce good looks.