December 1975. George and Kathy Lutz of Deer Park, New York recently married, this marriage her second following the death of her first husband. In part to begin a new life with her three children - Billy, Michael and Chelsea - especially as George tries to eke out his place in their life which is not to replace the memory of their father, George and Kathy want to buy another house in which they will live, they with a financial hurdle as George builds his contracting business. In nearby Amityville, they find what they consider the perfect waterfront colonial which they are surprised is just within their price range. After falling in love with the house, they learn that the reason for the low asking price is that one year previous, the former owners, the DeFeos, were murdered in the house. With this information in hand, they proceed to buy the house anyway, with George planning to turn the basement into an office for his business. Before buying the house, they are unaware of the details of the mass murder, where 23-year-old Ronald DeFeo Jr. had moved back in with his family, he living in the basement. He progressively began to feel possessed when finally on his 28th day in the house, he killed his parents and four siblings in the middle of the night, hearing voices telling him to kill them. After the Lutzs move into the house, some of the family members begin to see visions and have hallucinations, none of them telling the others for one reason or another. Slowly, the forces within the house begin to consume them to various degrees where they know that something is not quite right. The questions become if they will figure out that there is a force overtaking them before they are no longer able to get away, or if they are doomed to the same fate as the DeFeos on the 28th day of their residence. If the latter be the case, there will be the next Ronald DeFeo Jr. who will be the one of who the rest of the family needs to be wary.