Scorned by his colleagues for believing in the existence of ghosts, Dr. John Montague decides to prove his theory. He rents the Hill house, a warped, evil estate near the town of Hillsdale. The Hill House was built by Hugh Crain, eighty years before Dr. Montague and his company's occupancy, for his two young daughters and wife. In an unfortunate and unlikely accident, when she was first to see the house, Mrs. Crain's carriage fell over in the driveway, and she was crushed to death beneath. Later, he remarried and he, his new wife, and daughters took residence in the old house. This new wife was eventually plagued by consumption, and so Hugh Crain took her to various health clinics until her death, leaving the young girls at home to play by themselves. When eventually he died, the sisters who loved the house their father had built claimed it as both of theirs, until the younger sister got married and moved out. She wanted to take the dishes with her, however the older sister would not allow it, saying that the dishes belonged not to her, but to the Hill House. This grew into a long, hateful dispute and eventually a lawsuit when things began to go missing. Alone, the older sister took a companion into her home, a girl from Hillsdale. She stayed with her until her eventual death due to pneumonia, and there was some speculation of neglect. The younger sister's rages fell upon her, now, instead of the previous owner of the house. The girl lived in the house for a reasonable amount of time, before hanging herself from the balcony. The house fell to the Sandersons, cousins of the companion, and the first moment the younger sister stepped onto the property to harass the new owners, she is taken into custody of the police. The Sandersons made up the house as if they were planning to live in it, however they stayed there for only a few days before promptly leaving.
To aid him in his studies, Dr. Montague decides to hire several assistants. After sending many a letter and getting only a few back, these are narrowed down to three people. Luke Sanderson, sly, cunning, and a bit of a thief, comes as a representative of the family owning the house. Theodora (just Theodora), who has been proven to have some bit of psychic ability in lab tests, also accepts her invitation. The final assistant is Eleanor Vance. When she was young, shortly after the death of her father, rocks had fallen for days onto her house. She naturally blamed her sister for this, or possibly the neighbors.
Eleanor lives in the city, where she cared for her mother until her death. As a result of shutting herself in during this time, she is a bit of a recluse, and not particularly good at socializing. She now lives with her sister, her brother-in-law, and their small daughter, all of whom she hates. Despite denial by her roommates that she may take their shared car, she steals it anyways and drives up to the Hill House with it.
Eleanor is the first to arrive at Hill House, greeted by the unpleasant gatekeeper, Mr. Dudley, and led to her room by the terse Mrs. Dudley. Noting the odd structure of the house and the general eeriness surrounding it, she is terrified up until the point that Theodora waltzes in, who she deems much braver than herself. The explore the grounds together, in the process becoming good friends, until Luke arrives with Dr. Montague, and they gather for dinner and a meeting. He tells them his intentions, and, reluctantly, the history of Hill House, leaving them all very thoughtful. At the end of the night, Eleanor and Theodora go up to bed, and following, as usual, Luke and Dr. Montague. There is no disturbance for that night.
The following day, they eat breakfast, hardly able to find their way in the house, and then explore within it. They happen upon a cold spot in front of the nursery, where the gazes of two statues meet, and Dr. Montague makes not of it. They continue to explore the layout, and when they get to the point in which they go into the Library, then through to the turret and balcony, Eleanor finds that she can't go in, due to a repulsive death smell that only she senses. At the end of the day, they again dine, chat, and play chess. Eleanor and Theodora are again the first to go to bed, and following are Luke and Dr. Montague.
In the night, Eleanor is awoken to the sound of thumping and Theodora screaming. She goes through the bathroom and into her adjoining room to comfort her. Something is outside their rooms, and rapping loudly on the doors. They quickly lock them, and when the thing finally bangs on the door to Theodora's room and tries to get in, it finds that it can't, although it does not stop until Eleanor tells it to, at which point it laughs and goes away. Upon exiting the room, they find that Luke and Dr. Montague had not heard it because they had been up chasing a stray dog around the house all night, despite that the doors are closed.
On the third morning, nothing much happens, and they chat and discuss the events of the previous night. Dr. Montague announces that his wife will be coming to stay with them on Saturday. When in the Library, Luke finds a rather disturbing scrapbook about Heaven and Hell (particularly Hell), that Hugh Crain probably made to read his daughters to sleep. Later, before dinner, Luke is sent alone to ask Mrs. Dudley for coffee and comes back, distraught, and leads them to the dark hallway. Scrawled on the wall in chalk is a large message reading, "ELEANOR COME HOME."
The next day, Eleanor again hears Theodora screaming. She had opened her door to find that her entire room was splattered with paint-like blood. It stained the walls, the bed, and most devastatingly the clothes. She is forced to wear Eleanor's for the time being. Eleanor is horrified to find that, on the wall, in blood, is written "Eleanor come home."
When Saturday comes, Mrs. Montague does not arrive until dinnertime, and she brings an educator named Arthur with her. They refuse to hear anything about what has happened in the house, saying that ghosts are to be commiserated with and only wish to be remembered. After dinner, they set up a session with "Planchette," a device similar to a Ouija board. They later announce their results to the skeptical group, telling them an unlikely story that there was a nun buried alive, possibly in a well on the property. They also go into saying, however, that Planchette mentioned Eleanor, saying that she wanted to go home. Eleanor is greatly disturbed by this. She blames everyone around her for trying to trick her, particularly Theodora, who she also blames for writing on the walls. That night, Mrs. Montague sleeps in the nursery, and Arthur sleeps in the room across the hall. When the banging on the doors starts again, Dr. Montague, Eleanor, and Theodora all flee to Luke's room. The rapping on the doors continues, and when it reaches their door, it follows the same routine as the before. Instead of going away, however, it continues to laugh as the room begins to shake, toss, and turn beneath their feet. Eleanor faints and wakes up on the bed, everyone else looking haggard and the worse for wear.
In the morning, Dr. Montague tries to comfort his wife, but finds out that she didn't hear anything at all. Arthur heard nothing as well. They try another session with Planchette, however receive no results due to the fact that Planchette is "offended" from insults the previous night. Dr. Montague tries to measure the cold spot, however finds that his hands can't hold onto the measuring tape in the extreme chill, and the thermometer picks up absolutely nothing. Nothing much happens in the evening, until the nighttime. While Eleanor lies half-awake in bed, she thinks of all her false hatred for the other residents of the house, and in a fit of insanity, decides to run wild. She dances through the hallway, pounding on all the doors like the ghost did in previous nights, and runs away. When they find that she is missing, they run around the house looking for her. She hides from them, pretending that it's a game, and finds herself cornered near the library. Her only choice is to force herself to go in or be found, so she runs into the library, breaking whatever spell keeps her out. She waltzes up the stairs to the brittle, unsafe balcony and tries to unlatch the nailed-shut trapdoor to escape, while everyone runs into the library after her. Luke gently coaxes her down as she comes out of her madness, scared out of his own mind because the stairs have been rotted away from the wall. when she steps down, Eleanor apologizes, not quite knowing the extent of what she's done.
The next morning, Eleanor, despite her protests, is sent home. Theodora finds that her clothes aren't stained anymore, and she no longer has need of the borrowed ones. Whatever bond Eleanor has with the house is broken, and she becomes herself again while on the road, in her mind, reversing everything that has been done.