In New Orleans, in 1850, Julie Marsden, a strong-willed Southern belle, is engaged to marry Preston Dillard, a prominent New Orleans banker with an equally strong mind. Their struggle for supremacy in the relationship comes to a head the night of a traditional ball to which unmarried women are expected to wear white, but Julie defiantly insists on wearing red. Pres is shocked, but ultimately agrees to escort her. At the ball, Julie begins to regret her decision, but Pres forces her to dance, and afterward ends their engagement. In disbelief, Julie waits for Pres to apologize, but he stands his ground, leaving for the North on business. When he returns, she humbles herself in front of him, begging for forgiveness, but it is too late. Pres has married a Yankee, Amy Bradford, and asks Julie to accept his wife without bitterness. The growing threat of yellow fever in New Orleans has forced Julie and her Aunt Belle to move to their country plantation. There they entertain the Dillards, Pres's younger brother Ted, and one of Julie's persistent suitors, the rebellious Buck Cantrell. At dinner, Pres and Buck argue politics, but Pres is called to town and it is Ted who finishes the argument in a duel with Buck. Buck is killed, and Pres is struck down with fever. Julie sneaks through the fever line with the help of her servant, Gros Bat. In town, Dr. Livingstone tells Julie that Pres must go to the leper colony for quarantine. Amy, accompanied by Ted and Aunt Belle, follows Julie, and as Pres's wife, she insists on attending to him. In a final confrontation, Julie convinces Amy that her ignorance of Southern ways means certain death for them both. Amy acquiesces, and Julie rides into the night at Pres's side.