Late in the Civil War, three Confederate soldiers escape from a Union prison camp in Missouri. They soon fall into the hands of pro-Confederate raiders, who force them to act as "outriders" (escorts) for a civilian wagon train that will be secretly transporting Union gold from Santa Fe, New Mexico, to St. Louis, Missouri. The three men are to lead the wagons into a raider trap in Missouri, but one of them starts to have misgivings....