How does Heathcliff gain possession of Wuthering Heights? How does this acquisition further his ultimate goal?

Heathcliff has mysteriously amassed some sizable wealth. He returns and lends money to Hindley who is now almost constantly drunk. Heathcliff knows that Hindley will increase his debts and put Wuthering Heights up for collateral. When Hindley finally dies, Heathcliff inherits the manor. Heathcliff however has his sights set on Thrushcross Grange.