While he is gone, Catherine continues to court and ends up marrying Edgar. Their happiness is short-lived because they are from two different worlds, and their relationship is strained further when Heathcliff returns. Relationships are complicated even more as Heathcliff winds up living with his enemy, Hindley (and Hindley's son, Hareton), at Wuthering Heights and marries Isabella, Edgar's sister. Soon after Heathcliff's marriage, Catherine gives birth to Edgar's daughter, Cathy, and dies.
Heathcliff vows revenge and does not care who he hurts while executing it. He desires to gain control of Wuthering Heights and Thrushcross Grange and to destroy everything Edgar Linton holds dear. In order to exact his revenge, Heathcliff must wait 17 years. Finally, he forces Cathy to marry his son, Linton. By this time he has control of the Heights and with Edgar's death, he has control of the Grange.
Through all of this, though, the ghost of Catherine haunts Heathcliff. What he truly desires more than anything else is to be reunited with his soul mate. At the end of the novel, Heathcliff and Catherine are united in death, and Hareton and Cathy are going to be united in marriage.
