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
Like the Exposition Stage from our Classic Plot Analysis, Act I is all about giving us the information we need to understand the story to follow. We learn about Eleanor, her personality, and her dreams while she jacks her family car and drives to Hill House. We also learn about her new roommates Theodora, Luke, and Dr. Montague. Dr. Montague lets us in on the history of Hill House and plays tour guide through its haunted hallways. By the time Act I ends, we feel like we're part of the group and spending the night at Hill House ourselves.
Act II
Act II or, as we like to call it, "The Conflict Happens Act," features Hill House going medieval ghost-story on its guests and just generally doing its crazy thing. It knocks on doors, creates cold spots, tags Theodora's room with bloody graffiti, and manifests a bunch of phantasmal voices and images. It's a classy haunted house all the way.
But conflict arises between our friendly neighborhood ghostbusters as well. Eleanor undergoes a love-hate relationship with her new friends, sometimes feeling at home within the group but at other times feeling separate and alone. Her own angst and self-centeredness begin to push her further and further away from the group. To compensate, she identifies Hill House more and more as the place she truly belongs, the one entity that really "gets" her. Act II ends when Eleanor has become possessed under Hill House's spell.
Also, Mrs. Montague and Arthur arrive during this act because we could really use some comic relief.
Act III
The tension gets high in Act III, as Eleanor wanders the house like a ghost before deciding to climb the iron stairway. Once Luke saves hers, we move toward the resolution of the story. Eleanor is told she must leave Hill House for her own safety. Before she goes, she says her goodbyes, and it seems like all the conflict, plot, and relationship threads are nicely wrapped up. Right?
Wrong. Eleanor has no desire to leave Hill House, and so she commits suicide by running her car into a tree. Her story is brought to a violent and sudden resolution. Then we learn what the other ghostbusters do after leaving Hill House. As for Hill House, it keeps on keeping on in its solitary place among the hills.