For a three-act plot analysis, put on your screenwriter’s hat. Moviemakers know the formula well: at the end of Act One, the main character is drawn in completely to a conflict. During Act Two, she is farthest away from her goals. At the end of Act Three, the story is resolved.
Act I
Lockwood arrives and Nelly Dean begins to tell the story of the Earnshaws and the Lintons. Flashback time: Mr. Earnshaw brings Heathcliff into the family. Everyone treats him terribly, but then Heathcliff and Catherine fall in love. She chooses social status over romance, marrying Edgar Linton and moving into Thrushcross Grange.
Act II
Heathcliff is tormented by the loss of Catherine. He disappears for a while only to return and begin avenging himself on Hindley and, by extension, everyone else. Catherine dies in childbirth.
Act III
Now that Catherine is dead, revenge is a full-time job for Heathcliff. His brutality and scheming kills off just about everyone, including himself. Cathy and Hareton are the only ones who remain. Their love suggests a new era of hope.