Mr. Earnshaw walks home from Liverpool with a dark, nameless child, and the household names him Heathcliff, for a dead Earnshaw boy. Catherine Earnshaw loves him and marries the richer neighbor, Edgar Linton, anyway, and Heathcliff spends the rest of his life taking both households apart for it — patiently, legally, through the next generation. Catherine dies at the halfway mark, and the second half belongs to those children; that is where first-time readers stall. Brontë tells almost all of it secondhand: the housekeeper, Nelly Dean, relates the history to Lockwood, the new tenant, who writes it down, and she is implicated in much of it. Almost nobody is likeable. Joseph's dialect is close to unreadable. Not a romance — a haunting with a property deed attached.
Wuthering Heights is 116,538 words. At an average adult reading pace of 300 words a minute that is about 6 hr 28 min, or roughly 4 hr 51 min if you read quickly and 9 hr 43 min at a more deliberate 200 words a minute.
That count is measured from the complete public-domain text rather than estimated from a page count, so you can compare all the books side by side.