Valmont has had some success recently in the Tourvel-department, as he brags to the Marquise in Letter Twenty-one. His new plan is to have complimentary things about himself reported back to the Présidente through the manservant she employed to follow him. Valmont first has one of his own servants go to the nearest village to find out if anyone is in distress. Once he has secured a household with bad debts and no overly attractive women, because she might make his charity seem suspicious, he sets out to do a good deed. The Présidente's servant gets a good workout trying to follow the Vicomte through the countryside, but they finally arrive in the village. The needy family receives enough money to pay their debts. Valmont thoroughly enjoys the pleasures of doing good and anticipates being repaid in full by Tourvel's appreciation.

Madame de Tourvel is indeed impressed. She gushes to Madame de Volanges in Letter Twenty-two that she must reverse her judgment of the Vicomte's character. Also, she announces that she and Madame de Rosemonde are planning to make an additional contribution to the family in need.

In Letter Twenty-three, Valmont continues to describe his recent interaction with Tourvel. By now she has revealed to him her knowledge of his good-Samaritan activity. She takes him back to the village with her when she goes to make her own contribution, and later that evening, he is able to get her alone in the drawing room. There, he confesses his love. Tourvel is shocked and bursts into tears, exclaiming, "Oh, wretched woman!" ("Ah! Malheureuse!"). Then they are interrupted, and the Présidente flees to her room. Valmont follows her and sees her through the keyhole on her knees in fervent prayer. At the time of writing the letter, Valmont is sleepless, but cheerful, closing with a little piece of flattery. No matter how much Madame de Tourvel preoccupies him, he will always take the time to think of Merteuil.

Letter Twenty-four is Valmont's follow-up to his confession of love. He begins by expressing his regret at having told Tourvel anything at all about his feelings. But this regret quickly becomes indignation that Tourvel would pass judgment on him so quickly, especially when she had once seemed so just to him. He begs her to give him her care instead of her disdain. He asks that she indulge him by teaching him, by helping him walk along the path to goodness.

Finally, the Vicomte writes a third letter (Letter Twenty-five) to the Marquise, to inform her of his continuing progress with Tourvel. He has recently been admitted to her bedroom, where she is playing sick in order to avoid his company. While there, he has the chance to take her pulse, which gives him quite a thrill, and he leaves her his letter. She replies to him later in the day, in what he calls "hypocritical" terms. He encloses this letter so that the Marquise may read it and signs off with the suggestion that she and he should discuss Cécile at some time in the near future.

The letter that follows (Letter Twenty-six) is the letter in question. Tourvel expresses regret at having responded to Valmont's confession with so much emotion. She assures him that she will never return his feelings, and that she had assumed that he had too much respect for her to address her in such a way. In her eyes, he has ruined everything.