At the height of the Civil War, a gang of supposed Confederates, headed by Alex Morel, raid all gold shipments from Oro Grande, California, bound for Washington. Captain Steve Clark is recognized as a Union Secret Service agent by Morel's accomplice Trina Dessard, along with his friend Idaho Jones, is ambushed in the baggage car and sent to almost certain death when the car is un-coupled and plunges down the mountainside.