Once things start to happen the only people who see what is going on are George and the little girl. The evil in the house starts to play with George's mind. One of the most terrifying things happens in the bathroom. I can't tell you how terrifying it would be to be attacked by a ghost while using the bathroom in the middle of the night. That part always creeps me out. There are some intense scenes in this movie that when I saw this for the first time in the theater it gave me nightmares. It was great.
Now here is the part that I describe what is going on with the house in this movie. If you wish to learn this on your own by watching the movie I would suggest stopping the review here and skipping to the last paragraph for the rating. The house is part of a hidden torture chamber. A reverend in the Puritan days was torturing and experimenting on the native Americans that lived on the land first. The victims were sliced and skinned and subjected to all kinds of other horrible violent acts. Once George's mind is completely poisoned by the evil reverend who possesses the house he tries to kill his family.