Nelly, troubled by Heathcliff's growing influence, recalls a fearful visit toward Wuthering Heights. On the road she sees the old guide-post and is overwhelmed by memories of Hindley as a child, which makes her superstitiously anxious to check on him. At the gate she finds Hareton, now rough, profane, and hostile; he throws a stone at her and reveals that Heathcliff encourages his wildness while Hindley neglects him.

When Hareton goes to fetch Hindley, Heathcliff appears instead, and Nelly flees. The encounter confirms Nelly's fear that Heathcliff spreads corruption, so she resolves to guard Thrushcross Grange more closely. Soon afterward, Nelly secretly sees Heathcliff approach Isabella in the courtyard, restrain her, and embrace her, despite having told Catherine he despises Isabella.

Catherine discovers Nelly watching and confronts Heathcliff. Catherine warns Heathcliff to leave Isabella alone, but Heathcliff claims he may use Isabella if she allows it and accuses Catherine of having treated him cruelly. Heathcliff declares that he will make use of Isabella's attachment as revenge, not directly against Catherine but through the misery it will cause around her.

Nelly tells Edgar what has happened, prompting Edgar to come to the kitchen and banish Heathcliff from the house. Catherine, furious at Edgar for trying to summon servants rather than fight Heathcliff himself, locks the door and throws the key into the fire. Heathcliff mocks Edgar's fear, but when Heathcliff pushes Edgar's chair, Edgar strikes Heathcliff in the throat and leaves to get help.

Heathcliff wants to retaliate violently, but Nelly convinces him that servants are coming with weapons. Heathcliff breaks the lock and escapes. Catherine, agitated, retreats upstairs and tells Nelly to warn Edgar that she may become seriously ill, partly to frighten him and regain control of the situation.

Nelly refuses to support Catherine's manipulation. Edgar later asks Catherine to choose between him and Heathcliff, and Catherine responds with a violent fit. Nelly exposes that Catherine had planned to use illness as leverage, enraging Catherine, who locks herself in her room and refuses food. Edgar withdraws to the library, then warns Isabella that if she encourages Heathcliff, he will sever their sibling bond.