After their parents are killed by Union soldiers, Jesse James (Audie Murphy) and his brother Frank (Richard Long), along with the rest of their gang, ride into Kansas looking for William Quantrill (Brian Donlevy). Seeking revenge against the Union, Jesse wants to join Quantrill's Raiders, who are plotting to claim Kansas for the Confederacy. The more time Jesse spends with Quantrill, however, the more he realizes that Quantrill isn't a hero fighting for the South, but a murderous madman.