The marriage settlements come back formalized from the lawyer, and Lovelace proceeds to pursue a license. He encounters unexpected difficulties with this, because he cannot prove that Clarissa’s parents have consented to the marriage. Clarissa’s happiness makes their relationship smooth and pleasant, and Lovelace’s vicious resolve falters several times. When it does, he reads over Anna’s insulting letters to stir up his desire for revenge.

Belford again writes to admonish Lovelace and ask him to give up the plot. He writes of Clarissa’s perfection and pleads with Lovelace not to debase it. He makes fun of Lovelace’s contrivances, calling them trite, stale, and poor. Lovelace responds indignantly to the latter accusation.

The next letter is written at eleven o’ clock at night. Lovelace is about to spring some new evil. Clarissa has gone to bed, and Lovelace is going to sneak into her room, hoping that if he surprises her in sleep, she will not resist him. However, his body seems to be rebelling against his plan: he speaks to his heart, his knees, his fingers to tell them to be steady. He’s about to give up the idea when someone yells “Fire!” A maid has set the kitchen curtains on fire, and there is no real danger. But there is a commotion, and Clarissa comes to her door half-dressed and about to faint with fear. Lovelace runs to her and takes her in his arms. He is enraptured to be holding her. Concerned for her health, he puts her on her bed and sits on the side to show he means no harm.

As she recovers her senses, Clarissa nevertheless accuses him of treachery. She assumes that the fire was a trick. Lovelace clasps her in his arms again. She struggles and begs him to let her go, appealing to his mercy and duty to protect a defenseless creature. He continues to kiss and caress her and she calls for help. Thinking Lovelace is about to rape her, she looks for something to kill herself with. Finding nothing, she sinks to the floor, embracing Lovelace’s knees, and begs for mercy. He is softened and promises her safety if she will promise to forgive him. She does, and he leaves her alone. He says that the trial has been a triumph for her and for her sex.

Clarissa breaks her promise and refuses to see Lovelace for a week. She will only communicate with him by letter, and in her notes she accuses him of betraying her and says that she will only think about seeing him again if it is her only route to reconciliation with her family. Lovelace tells Belford that if Clarissa would show love for him and confidence in his honor he would marry her and be hers forever. But he is not quite resolved; he reflects on the intricacies of his plots, on her distrust of him, and on the fact that she is superior to him and they both know it. He cannot imagine having a superior wife. He admits that Anna is right, that Clarissa shines even in a time of suffering.

Clarissa escapes. Lovelace is beside himself. He learns that she had told Dorcas she would stay in her room for a week and asked her to bring some rolls so she would not have to leave to eat. Dorcas had taken her to the kitchen to prove that the fire was real and Clarissa appeared surprised. She had sent Will, Lovelace’s servant, out with letters for Anna and Lovelace and took advantage of his absence to sneak out. Some time had passed before she was missed, although she had attracted attention in the neighborhood by her hurry, and a man had seen her enter a coach and overheard the direction she had given the driver. Will sets out to find her.