Based on history and a novel by Lyle Saxon, pirate Jean Lafitte helps General Jackson defeat the British at New Orleans.
In August 1814 Dolly Madison (Spring Byington) directs the evacuation of the White House before the British arrive and burn it. In New Orleans Jean Lafitte is wanted for $500. Annette de Remy (Margot Grahame) says good-bye to her sister Marie as she boards the Corinthian. Senator Crawford (Ian Keith) tells Jean Lafitte (Fredric March) that the British will give him money. Dominique You (Akim Tamiroff) sells goods in a pirate market. Lafitte asks Annette to marry; but she asks him to give up piracy. Gov. Claiborne (Douglass Dumbrille) arrives, and Lafitte says he has not attacked U. S. ships. Captain Brown (Robert Barrat) burns a U. S. ship in defiance of Lafitte and makes the only witness Gretchen (Franciska Gaal) walk the plank. Lafitte in a boat rescues her. He asks Brown about the people who died and hangs him. Lafitte orders Beluche (Anthony Quinn) to keep Corinthian things from being sold. Gretchen says that Lafitte is not a gentleman. Men fear she will talk, but he makes her his servant. When the British arrive, he has Dominique lock her up. Captain McWilliams gives Lafitte letters offering gold, land, and pardon and threatens him. Lafitte asks for a week to talk with his men but persuades them to fight for America.
Lafitte tells Gov. Clairborne he will fight, and the letters are sent to General Jackson. Lafitte calls on Annette and says he is respectable; but her Aunt Charlotte tells him to leave, though Annette says she is going to marry him. Crawford suspects the letters and advises Andrew Jackson (Hugh Sothern) to kill Lafitte. Lafitte tells Gretchen to go home, but she refuses. The American ships fire on the welcoming pirates at Baratarian Bay; but Lafitte stops them from firing back and orders a retreat to the bayous as he waves the American flag. Gretchen tries to help trapped Dominique, who is captured. In a canoe Gretchen tells Lafitte that she loves him.
Crawford advises Jackson to surrender New Orleans; but Jackson keeps his plans secret and asks for help. Lafitte comes in his window with a pistol and demands his men; but Ezra Peavey (Walter Brennan) enters with a musket. Lafitte offers Jackson needed flints and powder. They learn the English are advancing and make a deal. Lafitte duels Crawford with a sword to get his men out of jail and kills him. Lafitte gives orders to Dominique and Beluche. Gretchen puts on a uniform. Lafitte and his men join the line with artillery. The British march in lines and are mowed down.
Dominique eats and asks Gretchen to marry; but she loves Lafitte and wants to go to the ball. Dominique gives her a dress and jewels. Jackson is honored, and Lafitte enters to acclaim. Lafitte dances with Annette. Dominique enters with Gretchen, who reminds Lafitte how they met at sea. Annette says Gretchen's dress was her sister's on the Corinthian. Gretchen is questioned by Gov. Claiborne and Annette. Lafitte makes plans to sail and announces that the Corinthian was sunk, and all but one were lost. Lafitte is tied up, but Jackson gives him the one-hour start he promised him. On ship Lafitte finds Gretchen.
Lafitte was pardoned by President Madison but did go back to privateering. History gives context and meaning to this adventure story as "rats without a country" fight for their new home in America, suggesting that the line between military adventures and criminal piracy is blurred.