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.
The next victim is Confederate Army Captain Clay Randolph who has discovered that Morel is connected with a group of Prussian spies who have been using the stolen gold to initially finance Prussia's wars but later to buy Alaska from the Russian Empire as a "club over Canada"; hed gives Steve a clue before he dies.
Aided by the San Francisco Secret Service, Steve escapes and returns to Oro Grande where he and Idaho round up the spies.
Cline writes that Raiders of Ghost City had a "good cast and production values...It came off quite well.