Bette is a poor spinster, a frequent visitor at her cousin Hulot’s household. When the story opens, the Hulot family fortune has been decimated by Baron Hulot’s mistress. He spends all his money on her, leaving his wife, Adeline, and daughter, Hortense, to struggle meagerly along. Hortense, whose dowry is shrinking daily, mindlessly amuses herself by teasing Bette about her "lover", the sculptor, Count Steinbock, who lives above Bette’s apartment. Bette treats the sculptor maternally but loves him with a jealous affection.

Hortense decides she must meet Steinbock and the two fall in love at first sight. Though Steinbock has little money, Adeline agrees to their marriage, but the engagement is kept from Bette. Baron Hulot’s mistress leaves him and he becomes invoved with Madame Marneffe, the wife of one of his employees.

Cousin Bette is bitter towards the Baron and his family because they treat her like a servant. When she hears about Hortense’s engagement to her friend Steinbock, she determines to destroy the whole family. Bette introduces Crevel (whose mistress Hulot once stole) to Madame Marneffe and he becomes a rival lover. Bette also anonymously has Steinbock imprisoned for his unpaid debts.

Meanwhile, Madame Marneffe seduces Steinbock. She then secures her power by telling each of her lovers that he is the father of her unborn child. Hulot reaches the end of the line shortly thereafter, when it is discovered that he has been stealing money from the government. Hulot’s brother dies of grief and Hulot himself goes off to live with a seamstress in the slums.

Madame Marneffe and Crevel also meet miserable ends. Several months later, Adeline discovers her missing husband while on a charity mission. He comes home, but soon seduces the maid. Adeline then dies, her emotional reserves exhausted.