Not a Rowdy Yates in sight in this western set in a stop over for the California to St Louis mail stagecoach run. The two staff are warned that four dangerous outlaws are in the area, and together with a female stage passenger and her baby they wait patiently for the word to go round that these men have been caught. Can you guess where the outlaws decide to hide out while they plan a large gold robbery? What follows is a film that concentrates on small details (like attempts to slip a warning note to a passing stage, or to reach a hidden gun that the bad guys don't know about) as the captives try anything to get away from the outlaws.

In 1860, Easterner Tom Owens works at the Rawhide Pass relay station of the "Jackass Mail," a stagecoach line carrying mail and passengers between San Francisco and Saint Louis. Rawhide, which is halfway between the two destinations, is a desolate place, and Tom looks forward to his imminent departure. One day, Tom and boss Sam Todd welcome the eastbound coach, driven by Gil Scott. As the passengers, including Vinnie Holt and her young ward Callie, eat, Tom and Sam are warned by soldiers that notorious bandit Rafe Zimmerman and three other convicts have escaped from prison. Fearing that Zimmerman and his henchmen are lying in wait further up the line, Sam and Tom force Vinnie and Callie to stay behind when the coach departs. Vinnie is furious, but despite her protests that she will lose her job, Tom insists that she stay until the following day. Taking Tom's pistol, Vinnie then storms off to bathe in a hot springs with Callie. Later that afternoon, Tom is approached by a man claiming to be a deputy from nearby Huntsville. When Tom and Sam lower their guard, however, the man reveals himself to be Zimmerman and calls in his compatriots, Gratz, Yancy and the psychopathic Tevis. Zimmerman informs Sam and Tom that he will let that evening's westbound stage pass through unmolested, but will rob the following day's eastbound coach of its $100,000 cargo. When Tevis finds one of Vinnie's dresses, Zimmerman assumes that she is Tom's wife, and Tom does not reveal the truth. As Vinnie returns, she is captured by Tevis, and Tom warns her to keep quiet about her identity. Vinnie is reluctant to cooperate, but Tom explains that because the bandits need him to take care of the arriving stagecoach, they will not hurt her or Callie. Tom is chagrined to learn that Vinnie lost his pistol behind the water trough when Tevis grabbed her, and their dilemma worsens when Gratz and Tevis shoot Sam as he tries to escape. After being locked in Tom's room, Vinnie confesses to Tom that Callie is her niece, not her daughter, and that she is taking the child to her grandparents. Tevis leers at the beautiful Vinnie as she prepares dinner, but Zimmerman warns him to stay away from her. Before the stage comes, Tom writes notes for himself and Vinnie, alerting the driver to their predicament, but Vinnie is taken behind the station by Tevis, and Tom's note falls to the ground as he harnesses a new team of mules to the stage. While the passengers eat, Tom attempts to purloin a revolver, but Zimmerman catches him and returns it to its owner. The coach leaves without incident, although Zimmerman slugs Tom for his attempted theft, and Tevis tries to attack Vinnie. Tom rescues Vinnie from the lecherous Tevis, and Zimmerman beats him. Realizing that the bandits will kill them after robbing the coach, Tom steals a kitchen knife and begins to dig a hole through his room's brick wall. Tom and Vinnie spend a tense night chipping away at the wall, and in the morning, when Tom feeds the stock, he finds his note in the dirt. Gratz catches Tom retrieving the note and demands to see it, but because he cannot read, he believes Tom's lie that it is a letter from his father. When Tom returns to his room and resumes chipping at the wall, the knife gets flipped outside behind the house. Vinnie succeeds in getting it when she takes Callie to the outhouse, while inside, the animosity between Zimmerman and Tevis grows. An hour before the stage is due to arrive, Vinnie accidentally breaks the knife in half, and despairs because the hole is still too small for her to crawl through. Vinnie then quarrels with Tom, who admits that he has cooperated with the outlaws out of fear for his life. Zimmerman bursts in, and Vinnie, realizing how hard Tom has tried to protect her and Callie, kisses him goodbye. Tom prepares the fresh team of mules, while Vinnie, locked in their room, watches. Callie crawls through the hole in the wall while Vinnie is not looking, and Vinnie's frantic cries upon noticing her absence draw Tevis. Vinnie's screams increase as Tevis paws her, but he then begins to strangle her to quiet her. Zimmerman pulls a gun on Tevis to stop him, and Vinnie is returned to her room. Enraged by Zimmerman's actions, Tevis shoots him in the back, then kills Gratz when he protests Tevis' assumption of leadership. Tom runs to the water trough to retrieve his pistol, and the two men begin a shootout. Meanwhile, Yancy runs away, and Vinnie escapes from her room to search for Callie. Tom and Tevis hear the bugle call announcing the approaching stage, but Tom is forced to surrender when Tevis spots Callie and begins shooting at her. The coach's driver hears the shots and races toward the outpost, while Vinnie finds Gratz's rifle and shoots Tevis in the back just as he is about to kill Tom. The weary Tom and Vinnie then hug Callie and sit on the front porch to greet the stage.