Julie Marsden is a headstrong young woman living with her Aunt Belle in New Orleans in the early 1850s. She's engaged to Preston "Pres" Dillard, a banker and a fine catch, but Julie's willfulness dooms the relationship. She has to get her way in everything, such as refusing to change to proper attire for her engagement party and walking unchaperoned into the bank to demand that Pres leave a board meeting and take her dress-shopping for an important ball. Because Pres tries to teach her better, she flaunts his authority and everyone else's by choosing a red dress for the ball, which is taboo as all unmarried girls are to dress in virginal white. Pres is furious, but escorts her to the dance anyway. When she sees how everyone shuns her, leaving her and Pres alone on the dance floor, she begs him to take her home, but he refuses and completes the dance to the end as punishment. They end the night with her slapping him and him taking his leave of her and moving North.
When Pres finally returns to New Orleans, Julie intends to make up with him and readies herself in white. Pres tells her he is married. The shocked Julie can't believe they are finished and keeps after Pres to make him admit he still loves her. Her injured pride provokes her to go so far as trying to incite a quarrel between Pres and Buck Cantrell, her admirer, only Pres' brother Ted happens to be the one Buck quarrels with and challenges to a duel. Though older and more experienced, Buck is killed in the duel and Julie becomes a "Jezebel" to even those who care for her.
Then Preston, who has been helping a doctor in the Yellow Fever outbreak in the area, falls deathly sick himself. Seeing a chance for redemption, Julie goes to his wife Amy and convinces Amy to let her be the one to care for Pres in quarantine, channeling her indomitable will towards a noble cause at last.