Frédéric sets out desperately to find the twelve thousand francs needed to save Madame Arnoux. He tells Madame Dambreuse he needs the money to help Dussardier, who he claims has stolen something. He rushes to the Arnouxes’ house, but they’ve already left. He looks for Regimbart, who tells him that the lawsuit has already gone through. Regimbart pities Madame Arnoux.
Frédéric returns to Rosanette, who looks at Pellerin’s portrait of her dead baby and cries. Frédéric, wondering what will happen to Madame Arnoux, also cries. Madame Dambreuse finds out from Regimbart’s wife that Frédéric has given her money to Madame Arnoux, and cries. Then she vows revenge. She doesn’t let on to Frédéric that she knows what he did. Instead, she has him invite Deslauriers over, saying she must consult him about a legal matter.
Madame Dambreuse tells Deslauriers about the debts the Arnouxes owe her, the debts that Frédéric had once convinced Dambreuse to temporarily forgive. Deslauriers, looking for his own revenge against Madame Arnoux for refusing his advances, tells Madame Dambreuse to sell the debts at auction. He will have an agent buy them and then prosecute the Arnouxes.
In November, Frédéric sees a sign on the Arnouxes’ door declaring that all the furniture and other possessions are going up for sale. He finds out that Senecal has ordered the sale. He hurries home and accuses Rosanette of being responsible, but she denies it. They argue, and he leaves her.
One day, as Madame Dambreuse and Frédéric are riding in their carriage, Madame Dambreuse decides to visit the sale rooms. Inside, she goes straight for the auction of the Arnouxes’ possessions. Frédéric is horrified to see such familiar objects treated so haphazardly. Madame Dambreuse taunts him by buying something. Frédéric leaves her.
Frédéric returns to Nogent, hoping to still marry Louise. But he arrives just as Louise is marrying Deslauriers. He returns to Paris. There is fighting in the streets, and Frédéric sees Dussardier get killed by a policeman, who he then recognizes as Senecal.