Gunman River Hicks, along with twins Connor and Abby Mack, his wary teenage trail companions, stop in Abilene to catch their breath. But when Abby kills the sheriff's son in self-defense, they are forced to flee to Colorado, pursued by a vengeful posse. Signing on as regulators for the Rocky Mountain Railroad they are assigned to protect a gold shipment. Loaded with business magnates, miners, gamblers, and deadbeats, the train lacks only a spark to explode into violence. When the murderous Doyle Gang attempts to rob the train by blowing up the track, the outgunned trio are thrown in to bullet blazing danger. With the unexpected help of four Arapaho braves, whose presence on the train has bitterly divided the passengers, it's an all-out war against the combined fury of the Doyle Gang and the Sheriff's posse… This is one trip you'll never forget.