While waiting to pick up some furniture for his boss, Gail Martin, at the Trail Head, Arizona train depot, ranchhand Bob Jackson interrupts masked outlaws Stoney Dawson, Dakota and Fowler as they attempt to rob the incoming train. Bob is shot just as fellow hands Tim Holt and Chito Rafferty arrive to help, and a gunfight ensues. The outlaws flee unharmed, but Bob dies. Later, at their hideout, the outlaws report to boss Turk Thorne that the train safe was not filled with gold, as they had expected. Determined to steal some of the gold that periodically passes through Trail Head, Turk decides to enlist Dave Collins, a telegraph operator who once helped them on a robbery, to act as their "inside man" at the telegraph office. Aware that Dave is about to be paroled from prison, Turk writes a letter to the warden, claiming to be a rancher interested in offering Dave a job. The now-reformed Dave, who has written to his mother that he is a ranch owner, accepts the offer and leaves for Trail Head. Just outside town, however, Dakota and Stoney stop Dave's stagecoach and force him out at gunpoint. When Dave refuses to cooperate with the outlaws, they knock him out and start to carry him away. At that moment, Tim and Chito happen by and fire shots at the outlaws, who drop Dave and escape. After Tim finds a bandanna at the scene that he recognizes from the train holdup, he and Chito take Dave to Gail's Circle Bar ranch. There, Tim questions Dave, but Dave claims to know nothing about his attackers and states that he is an Easterner looking for work. Foreman Tim hires Dave, then reveals to Gail his suspicions that Dave is somehow involved in Bob's murder. Later, Dakota and Stoney see Tim and Chito in town and follow them to the Circle Bar, where they also spot Dave. The outlaws then spy on Dave as he reads a letter from his mother while tending to Gail's cattle herd. When Dave, upset by the letter, suddenly rides off, Dakota and Stoney stampede the herd, hoping to cause his dismissal. Tim and Chito arrive in time to stop the stampede and apprehend Dakota, whom they then deliver to the Trail Head jail. At the telegraph office, meanwhile, Turk kills Duke, the elderly operator, and sneaks off just before Dave shows up to send a telegram to his mother, asking her to postpone a proposed visit. Dave, who was seen by Sheriff Lacey, finds Duke dead and rides off just as Chito and Tim show up, looking for the sheriff. At the Circle Bar, Dave is saying goodbye to the smitten Gail when Tim and Chito return from town and accuse him of Duke's murder. Dave finally admits all but insists he did not kill Duke. Not completely convinced, Tim gives Dave a chance to prove his innocence by helping him to trap Turk. Tim then persuades the sheriff to hire Dave to work in the telegraph office and arranges for Dave to slip the incarcerated Dakota a blank-filled gun. After Dakota "shoots" the sheriff and escapes, he delivers a message from Dave to Turk, announcing a gold shipment the next day. Suspecting a trap, Turk, Dakota and Stoney find Dave romancing Gail in her buckboard and take them both prisoner. The next morning, Chito and Tim discover that Dave and Gail are missing and go to town in search of them. Sure that Dave has double-crossed them, the sheriff calls off the trap and tries to arrest Tim and Chito. Tim pulls his gun, however, and he and Chito flee. As the sheriff gives chase, he is spotted by Stoney, who reports to Turk that Dakota could not have shot the lawman. Though exposed, Dave insists that the gold shipment is indeed coming and is forced to accompany Turk and Stoney to the train depot, while Dakota guards Gail. Tim and Chito, meanwhile, elude the sheriff and track Gail's buckboard marks to the outlaws' hideout. After taking Dakota by surprise, Tim and Chito free Gail, then race to town to save Dave. They arrive just as Dave is opening the train safe for Turk, and after a brief fight, the outlaws are apprehended. Later, the now-exonerated Dave looks forward to a visit from his mother, as Gail has proposed he become the Circle Bar's owner by marriage.