Hill House is a mansion in a location never specified, surrounded by hills. Dr. John Montague, an investigator of the supernatural, Eleanor Vance, a shy young woman who resents caring for her demanding, disabled mother,[5] Theodora, a bohemian artist, and Luke Sanderson, the young heir to Hill House, meet there at Montague's behest. Montague hopes to find scientific evidence of the existence of the supernatural. He rents Hill House for a summer and invites as his guests several people whom he has chosen because of their experiences with paranormal events. Of these, only Eleanor and Theodora accept. Eleanor travels to the house, where she and Theodora will live in isolation with Montague and Luke.
The house's two caretakers, Mr. and Mrs. Dudley, refuse to stay near the house at night. The four overnight visitors begin to form friendships as Montague explains the building's history, which encompasses suicide and other violent deaths.
All four of the inhabitants begin to experience strange events while in the house, including unseen noises and ghosts roaming the halls at night, strange writing on the walls, and other unexplained events. Eleanor tends to experience phenomena to which the others are oblivious. At the same time, Eleanor may be losing touch with reality, and it is implied that at least some of what Eleanor witnesses may be products of her imagination. Another implied possibility is that Eleanor possesses a subconscious telekinetic ability that is itself the cause of many of the disturbances experienced by her and the others, which might indicate there is no ghost in the house at all. This possibility is suggested especially by references early in the novel to Eleanor's childhood memories about episodes of a poltergeist-like entity that seemed to target her home.
Later in their stay, the doctor's wife, the haughty Mrs. Montague, and her companion Arthur Parker, the headmaster of a boys' school, arrive to spend a weekend at Hill House and help investigate it. They, too, are interested in the supernatural, including séances and spirit writing. Unlike the other four characters, they do not experience anything supernatural, although some of Mrs. Montague's alleged spirit writings seem to communicate with Eleanor.
Much of the supernatural phenomena that occur are described only vaguely, or else are partly hidden from the characters themselves.[6] One night, Eleanor and Theodora are in a bedroom when an unseen force begins trying the door, and Eleanor believes after the fact that the hand she was holding in the darkness was not Theodora's. Later, as Theodora and Eleanor walk outside Hill House at night, they see a ghostly family picnic that seems to be taking place in daylight. Theodora screams in fear for Eleanor to run, warning her not to look back, though the book never explains what Theodora sees, but she babbles, laughs, and cries in fright.[7][8][9]
The others eventually come to believe Eleanor is the cause of the disturbances. Fearing for her safety, Montague and Luke declare that she must leave. Eleanor, however, now regards the house as her home and resists. Montague and Luke force her into her car; she bids them farewell and drives off, but before leaving the grounds of Hill House, she propels the car into a large oak tree to her implied death.
