Thérèse Desqueyroux opens in a court case. Thérèse was being tried for poisoning her husband with arsenic. Instead of being furious with her, he testified in her defense. Though there was strong evidence against her, the case is dropped.
When Thérèse is on her way home, she thinks about how her life has unfolded, leading up to the moment she decided to poison her husband, and how she should explain and confess to him later. We learn more of her backstory, though there is no conclusion, as the monologue is philosophical.
Instead of letting his wife go, listening to what she had to say, or showing her mercy, Bernard, Thérèse’s husband, begins his dictatorship over his wife. He moves her to his family’s house in an isolated forest, where she is kept away from the society she knows of, surviving on wine and cigarettes.
To make sure no one thinks of her confinement, Bernard takes Thérèse with him for an occasional visit to the public. The only people around Thérèse are the servants, and she is kept away from her daughter. If she tried escaping or doesn’t follow the rules, he tells her he will send her to prison.
Anne, Bernard’s sister is engaged, and Bernard hopes the marriage will proceed without problem. When Thérèse and Bernard are invited to a dinner party with Anne, and the public sees the state she is in, they are shocked. Bernard understands that he must let Anne go if he wants to scandal to simmer down.
When Anne’s wedding passes and Thérèse has recovered and is back on her feet, Thérèse leaves.
