n November 1864, during the final weeks of the American Civil War, a Union train pulls into Greensburg, Ohio. Beside passengers, troops and mail the train also carries the latest military invention of Dr. Gatling, the Gatling Gun. Only four such weapons have been assembled and one of them is being sent out West to be tested by Union troops. However, Confederate spies, led by Captain James S. Simmons, of the Georgia volunteers, are well informed regarding the presence of the Gatling Gun on the train. The Confederates, masquerading as Yankees, have set-up an ambush at Greensburg's railway station. When the train stops at Greensburg, the Confederate spies manage to attack and capture the crates containing the disassembled Gatling Gun. After leaving the scene, the Confederate team disperses and only Captain Simmons and Sergeant Guderman carry the Gatling hidden in an elixir salesman's wagon. The two Confederates must cross all Union states undetected and reach Confederate lines with the