Based on a French (1869) and English (1870) play, a responsible woman persuades her frivolous sister to marry the lawyer she loves and ends up taking over the home.
Gilberte "Frou Frou" Brigard (Luise Rainer) returns to a Louisiana plantation from Europe and wants a husband. George Sartoris (Melvyn Douglas) prosecutes men for stealing slaves and murder. When one tries to escape, George is wounded and shoots him. Frou Frou goes to New Orleans and sneaks into a party, meeting Andre Vallaire (Robert Young). Frou Frou has Andre buy gifts for George and her sister Louise Brigard (Barbara O'Neil). Andre tells his mother Madame Vallaire (Alma Kruger) he wants to marry Frou Frou. Louise hopes to marry George but learns that he loves Frou Frou. Louise advises Frou Frou to marry George. Frou Frou likes Andre but agrees.
Buying a toy for her son's fourth birthday, Frou Frou meets Andre back from France. Andre will act in the play with Frou Frou. George tells Frou Frou they are going to Texas so he can make laws; but she tells him to forget it. George asks Louise to help frivolous Frou Frou take care of his son. Louise moves in, and Frou Frou gives her the keys. Louise commands slave Pick (Theresa Harris), who complains to Frou Frou. Andre rehearses a kissing scene with Frou Frou. George waits up for Frou Frou, and Louise suggests he sleep in another room. George thanks Louise for running the house, and Frou Frou hears. Louise learns that George refused the offer in the west. Andre tells Frou Frou he loves her and that she is not happy. Frou Frou tells George she wants to take charge, but George wants to keep Louise. Frou Frou thinks that Louise loves a French count, but Louise refuses to marry him and tells George and Frou Frou she is happy there. Frou Frou accuses Louise of stealing her home and husband. Louise tells Frou Frou that George called her a toy wife and asked Louise to save his marriage.
Frou Frou goes off to New York with Andre, and his mother tells Louise and her father Victor Brigard (H. B. Warner) they must never see Frou Frou and Andre again. Victor collapses. Frou Frou signs over her half of his estate and gives her money to her son. Andre tells Frou Frou he is a broke gambler and must go back. George tells Senator Rondell (Walter Kingsford) he made his will and not to let Frou Frou see his son. George with Rondell challenges Andre to a duel. Frou Frou laments the harm and takes Andre's body to his mother. Pick cares for Frou Frou in a room with rent owed. Sick Frou Frou prays in church. Louise comes in to pray and embraces Frou Frou. Louise tells George she found Frou Frou; but he rejects Frou Frou. George tells Louise he is ashamed. Louise admits she loved him but does not now. George lets his son see his mother Frou Frou. George takes Frou Frou home. Frou Frou tells George that Louise loves him and dies.
This family tragedy results from a misguided marriage and is worsened by the dangerous custom of dueling. George selected his wife based on sexual attraction when her more mature sister probably would have suited him much better as a wife and mother of his children.