Newlyweds and their three children move into a large house where a mass murder was committed. They start to experience strange, inexplicable manifestations which have strong effects on everyone living in or visiting the house.
Anthony Montelli and his wife, Dolores, move into the house of their dreams with their children, Sonny, Patricia, Mark, and Janice "Jan". Things go well at first, but everything changes after it is discovered that there is a tunnel in the basement leading into the house from an unknown place.
A reporter moves into the ominous Long Island house to debunk the recent supernatural events, and finds himself besieged by the evil manifestations which are connected to a hell-spawn demon lurking in the basement.
In 1974, Ronald DeFeo Jr. murdered his family at their house at 112 Ocean Avenue in Amityville, New York. He claimed that he was persuaded to kill them by voices he heard in the house.
Teenager Belle Walker moves to 112 Ocean Avenue in Amityville, Long Island with her mother Joan, little sister Juliet, and brain death twin brother, James. The family's impetus for moving there was to be closer to Dr. Milton, a neurology hoping to treat James, who suffered an accident that has left him on life support. Upon moving in, Juliet tells Belle that James has been talking to her lately, "using a lot of curse words." One night, James Asystole, but is mysteriously revived and opens his eyes.