In Letter Fifty-one, which opens Part Two of Dangerous Liaisons, the Marquise de Merteuil scolds Valmont for the lack of attention he has paid her and her schemes lately. She asks him to make up for his bad behavior by gaining the Chevalier Danceny's confidence in order to encourage him to make love to Cécile. The Marquise is annoyed by the slow pace at which Cécile and Danceny's affair is progressing.

Valmont, meanwhile, continues his amorous siege of the Présidente de Tourvel. Letter Fifty-two is written in his standard style. He begs her to take his entreaties seriously and tells her that she is cruel for refusing him.

Next, Valmont replies to the Marquise de Merteuil (Letter Fifty-three) and he lets her know that Danceny has begun to confess the details of his relationship with Cécile.

The Marquise responds at much greater length (Letter Fifty-four). She complains about Danceny's ineptitude when it comes to romance. Cécile deserves a better lover, she says.

In Letter Fifty-five, Cécile writes to Sophie about the recent developments in her affair with Danceny. Apparently, Cécile is no longer able to resist: she has admitted her feelings and now hides nothing from her chevalier. She also announces that her friendship with the Marquise is getting warmer, and that she would be completely happy if only she did not have to marry Gercourt.

The Présidente de Tourvel continues to resist Valmont. In Letter Fifty- six, she emphasizes the comfort and stability of her current life and writes that she would be foolish to give these things up for an uncertain love-affair. She asks the Vicomte again to stop writing to her and tells him that this is the final letter he will receive from her.