What happens when Cathy disappears in Chapter 18? Where is she found?

When Isabella is near dying, Edgar goes away for three weeks and Cathy disappears; a worker saw her jump her pony over the fence, leaving the property. Worried, Nelly sets out for Penistone Crags, thinking Cathy headed that way. Nelly finds Cathy at the Heights, where luckily, Heathcliff is not at home. Cathy gets angry when the maid tells her that Hareton is her cousin.