Thérèse ​is a selfish woman who can never find peace or interest in her own life. Despite her husband being good to her, she's bored with him. She slowly grows to dislike everything about Bernard. One day, she decides that she's going to poison him even though she has no justification for doing so. The case goes to court and Bernard convinces them that Thérèse ​is innocent. François Mauriac writes:

"I am not considering myself m this matter. For the moment I am out of the picture. The only thing I am worrying about is the family. Every decision of my life has been dictated by the interests of the family. For the honor of the family, I consented to cheat justice. Let God be my judge."

His pomposity made Thérèse feel sick. She would have liked to tell him to say what he had to say more simply.

"For the sake of the family, the world must suppose that we are in complete harmony. I shall make it quite clear that I believe in your innocence. On the other hand, I shall do everything in my power to protect myself."

"Are you frightened of me, Bernard?"

In a low voice, he said "Frightened? No, merely disgusted."

Bernard is someone who is focused on others; this is a sharp contrast to Thérèse. Ultimately, he keeps her in her room to protect himself before sending her away to Paris and keeping their daughter with him.

Paris doesn't interest Thérèse either. She's a person who can't find interest in most things and feels constant boredom even when she's away from her obligations and familial connections. She almost seems empty even as she wanders the streets searching for entertainment.

Nevertheless, she still retained her old expensive habits. She couldn’t go out in Pans without spending money like water, it was the only way she knew of filling the emptiness of her life, the only way in which she could achieve, not happiness, perhaps, but at least a sort of drugged, besotted state of contentment. Besides, she no longer felt strong enough to wander the streets alone. The “pictures” had never been any help to her. Seated there in the semi-darkness, she felt defenseless against the great waves of boredom that engulfed her. The most trivial human creature whose movements she might watch in a cafe interested her far more than the shadows on a screen. But she no longer dared to give herself the amusement of spying on others, because, wherever she went, she inevitably drew attention to herself. Useless to dress in neutral colors, to choose retired corners. Something in her appearance, she did not know what, caused all eyes to fasten on her. Or was that just her imagination? Perhaps the trouble lay in her worried expression, her pursed lips.

Even a visit from her daughter doesn't create delight; though she resolves to help her win the man she loves, Thérèse realizes he's in love with her. She continues to captivate people without trying. First, it was her best friend's love; now it's her daughter's. She encourages him to let Marie know that he doesn't love her.

Still, though, Thérèse's daughter returns and brings her mother home with her. She wants her to find rest in the place she rejected years before—and Thérèse does. Even Bernard accepts her back, despite everything she's done. She's able to heal there. However, to continue the tragedy of her life, she doesn't have long to live. She decides to fight against it, saying:

Was this the end? As it happened, Thérèse was not feeling particularly...