Disguised as a man to serve with her husband as a soldier in the Confederate Army, Irish immigrant Katie Rose O'Reilly vows to remain in the ranks and seek revenge on Yankees after her husband is killed at Sharpsburg. When she falls and almost drowns in a swollen stream, Southerner Alexander Hart, a Yankee spy, saves Katie from drowning, then nurses her through a resulting fever, keeping his identity secret from the feisty and beautiful Rebel soldier even as he finds himself falling in love with her. Can Katie reconcile her loyalties with her love?