Cathy grows into a beautiful, smart, inquisitive, and willful thirteen-year-old. Edgar doesn't allow her to leave Thrushcross Grange unattended however, so she is entirely unaware of Wuthering Heights or anyone who lives there. One day she hears of some fairy caves at nearby Penistone Crags and begs Edgar to take her, but Edgar refuses since to get there they would have to pass Wuthering Heights
Cathy is nearly the spitting image of her mother, impulsive and wild. Yet just as Heathcliff has essentially imprisoned Hareton at the Heights to keep him un-civilized, Edgar keeps Cathy at the Grange to keep her civilized and a proper young woman.
Soon after, though, Edgar learns that Isabella is dying and rushes off to London to bring Linton back to the Grange. While he's gone, Cathy manages to escape Nelly and the grounds of the Grange. She heads off toward Penistone Crags, but meets Hareton along the way and immediately likes him. The two spend the day playing together.
Cathy and Hareton have a natural and mutual affection for each other, despite their opposite upbringing.
Nelly chases after Cathy and soon finds her at Wuthering Heights. Cathy refuses to leave when Nelly tells her to, however—she wants to stay with Hareton. Cathy's interest in Hareton turn to contempt, though, when she learns from Nelly that Hareton isn't the son of the master of Wuthering Heights. Cathy starts to order Hareton around, who much to her surprise and indignation curses back at her.
Yet Cathy also has been schooled in the ways of civilization, and just as Catherine was taught to look down upon the "rough" Heathcliff, Cathy is similarly disdainful of anyone who civil society says is beneath her.
A servant of Wuthering Heights then reveals that Hareton is actually Cathy's cousin. Catherine denies it with the argument that her father has gone to get her real cousin, who is the son of a gentleman, from London. Unhappy that the news of Edgar's trip to get Linton has been made public, Nelly hushes Cathy by saying that a person can have many cousins of all sorts of stations in life.
Cathy seems to think that class is set-in-stone reality; that if you are in one class you cannot possibly be related to anyone of another. But as Heathcliff's and Hareton's lives show, this is not entirely true. Though you are born into a certain class, circumstances can change things.
Finally Nelly and Cathy leave. On the trip back to the Grange, Cathy agrees not to tell Edgar about her trip to Wuthering Heights, since the news might anger Edgar so much that he would fire Nelly.
As a member of a lower class, Nelly is dependent on Edgar's goodwill in order to keep her job.