A Union cavalry officer is ordered to demolish a railway junction in the middle of Confederate territory, but finds his authority constantly challenged by a military surgeon assigned to accompany him. John Ford's Western, based on an actual Civil War incident, starring John Wayne, William Holden, Constance Towers, Hoot Gibson and Anna Lee.

A Union Cavalry outfit is sent behind confederate lines in strength to destroy a rail supply center. Along with them is sent a doctor who causes instant antipathy between him and the commander. The secret plan for the mission is overheard by a southern belle who must be taken along to assure her silence.