On the fifth day of Nelly Dean's imprisonment, Zillah enters the locked room and releases her. Zillah explains that Gimmerton believes Nelly and Cathy were lost in the marsh, while Heathcliff has claimed Nelly was merely kept until she recovered her senses. Zillah also reports that Edgar Linton is not yet dead, though Doctor Kenneth thinks he may live only another day, so Nelly immediately leaves to return to Thrushcross Grange.

Before leaving Wuthering Heights, Nelly finds Linton Heathcliff alone and questions him about Cathy. Linton says Cathy is locked upstairs because she is his wife and must not leave, and he repeats Heathcliff's claims that she only wants his money. Under Nelly's rebuke, Linton admits Cathy is miserable and ill, that Heathcliff threatened and struck her, and that Heathcliff crushed one of the portraits from her locket after she tried to keep it from Linton.

Nelly reaches Thrushcross Grange and tells Edgar that Cathy is alive and may soon return. Edgar, near death, briefly faints from the shock and joy, then learns enough of Heathcliff's scheme to understand that Heathcliff intends to secure Cathy's property through Linton. Edgar orders his will changed so Cathy's fortune will be held by trustees, but the servant sent for Mr. Green is delayed, and the armed men sent to retrieve Cathy return without her after Heathcliff refuses them access.

Before dawn, Cathy herself knocks at the Grange door, having escaped from Wuthering Heights. Nelly steadies her and urges her not to distress Edgar with complaints. Cathy and Edgar are reunited, and Edgar dies peacefully while looking at his daughter, believing he is going to his dead wife and that Cathy will one day join them.

Cathy remains dry-eyed beside Edgar's body until Nelly finally persuades her to rest. Mr. Green arrives late, after first going to Wuthering Heights, and Nelly concludes that he has sold himself to Heathcliff. Green assumes authority at the Grange, dismisses most servants, and the funeral is hurried, though Edgar's burial wishes are protected by his will and Nelly's resistance.

Cathy later explains that despair and the failed rescue attempt forced Linton into helping her. Terrified of Heathcliff, Linton fetched the key, unlocked and relocked the door without fastening it, and arranged to sleep with Hareton. Cathy escaped through her mother's former room by climbing down the fir tree, while Linton was punished for his part in her flight.