US army officer John Nelson spends time undercover as a civilian in an attempt to speed the construction of the east-to-west Kansas-Pacific Railroad, which is being delayed by saboteurs. Western, starring Sterling Hayden, Eve Miller and Barton MacLane.

Just before the Civil War (but after the South has seceded), Southern saboteurs try to prevent railroad construction from crossing Kansas to the frontier; army captain Nelson is sent out to oppose them. As the tracks push westward, Nelson must contend with increasingly violent sabotage, while trying to romance the foreman's pretty daughter Barbara.