Aglaya finds Prince Myshkin asleep on the bench in the park. He tells her of the events of the preceding night and morning. He believes Hippolite wished to evoke people's respect and the feeling of regret of his death. Aglaya offers the prince her friendship and says his mind is of a higher kind, something no one around her, except her mother, understands. Then Aglaya announces that she has decided to run away from home, and she asks Myshkin to help her. After the prince calls the idea absurd, she asks how he dared write her a "love" letter. He replies that it was no such thing and that he merely wrote to her as to a light.

Aglaya tells Myshkin that she is in love with Ganya and that she promised to marry him during a recent meeting with him near this same bench in the park. She says that Ganya, in order to prove the strength of his love, has burned his finger. The prince catches Aglaya's lie, as he saw Ganya the day before and remembers that his hands were in perfect condition. Aglaya admits to lying. She then says that when she read the poem about the poor knight, she was hoping to show Myshkin that she knew everything about what happened between him and Nastassya Filippovna.

They begin talking about Nastassya Filippovna. Myshkin says he does not love the woman, although he did come to Pavlovsk because of her. Aglaya says that Nastassya Filippovna has been writing letters to her, and she gives the letters to Myshkin. Nastassya Filippovna wishes to see Aglaya and the prince marry, at which time she herself will marry Rogozhin right away. Suddenly Madame Yepanchin finds the two sitting on the bench. Aglaya runs off. Madame Yepanchin and the prince follow her to the Yepanchins, where the prince stays a while and then shortly leaves for the Lebedev house.

Myshkin arrives at Lebedev's looking very happy. Kolya arrives and warns the prince about Ferdyshchenko, who left the house at seven o'clock that morning. As Kolya walks out, Lebedev walks in, complaining that 400 rubles were stolen from his coat the previous night. He thinks the potential suspects are General Ivolgin, Keller, and Ferdyshchenko; he seems to suspect the latter the most. Myshkin tries to divert attention away from the general, suggesting that it was most likely Ferdyshchenko.

Left alone, the prince reads the three letters Nastassya Filippovna wrote to Aglaya. In them, Nastassya Filippovna calls Aglaya perfection, far above herself, and says wants to see Aglaya as Myshkin's bride. That evening, the prince walks to the Yepanchins', but it is so late that most of them are either asleep or about to go to bed.

Myshkin then decides to take a walk to the park, where he encounters Nastassya Filippovna, who has come to see him for the last time. She asks the prince if he is happy, but she runs off before he answers. Rogozhin, who has been with her, tells the prince that they are planning leave the next day. Myshkin tells Rogozhin that the answer to Nastassya Filippovna's question is that he feels very unhappy.