After a lifetime of robbing banks and holding up trains, Jimmy "Slash" Braddock and Melvin "Pecos Kid" Baker are ready to call it quits, though not completely by choice. Sold out by their old gang, Slash and Pecos have to bust out of jail and pull one last job to finance their early retirement. The target is a rancher's payroll train. The catch is: the train is carrying a Gatling gun and twenty deputy U.S. marshals who know they're coming. Caught and quickly sentenced to hang, their old enemy, the wheelchair-bound, a bucket of mean, Marshal L.C. Bledsoe, shows up at the last minute to spare their lives. For a price. He'll let them live if they hunt down their old gang, the Snake River Marauders. And kill those prairie rats, with extreme prejudice.