The Amityville Legacy (2016)

In 1974, Ronald DeFeo Jr. uses a rifle to kill his entire family at 112 Ocean Avenue in Amityville, New York. Four decades later, the Janson family comes together to celebrate the fiftieth birthday of the family's widowed patriarch, Mark. Mark is a recovering alcoholic who lives in rural Nebraska with his dementia-addled mother, Jeanne, and pregnant daughter, Britany. Attending the reunion are Mark's other three daughters Julia, Jennii, and Breana, Breana's boyfriend, Daniel, Mark's son, Anthony, Anthony's boyfriend, Jade, Mark's sister in-law, Cheyenne, and Cheyenne's daughter, Schuylar. One of Mark's birthday gifts is a cymbal-banging monkey toy that was at some point taken from 112 Ocean Avenue. The monkey is inhabited by a demon, which takes on the form of Mark's abusive deceased father, Mr. Janson. The demon torments Mark (who is a devout Catholic) with visions of things like Breana and Daniel having premarital sex and Anthony and Jade engaging in S&M, with each of the hallucinations being punctuated by the phrase, "Stop me, daddy." The demon tells Mark that he must eliminate any and all threats to his family's unity, so Mark reluctantly kills Cheyenne, Daniel, and Jade.

After the triple homicide, the demon declares that just killing the "outsiders" was not enough; it informs Mark that his family members are all awash in sin, and that it is up to Mark to "save" them by killing them in order to send their souls to Heaven. Mark experiences a sexually explicit vision of himself and Julia, and afterward arms himself with a shotgun, which he uses to murder Jeanne, Schuylar, and all of his children except for Julia. Julia wounds Mark during a struggle, and escapes while Mark is distracted dealing with a pair of passing motorists; after killing the motorists, Mark collects the bodies of all of his loved ones and stacks them in a room in his house, where he proceeds to commit suicide.

A week later, a psychic paranormal investigator visits the Janson house, and encounters the demon, which has possessed a paperboy. The demon brags about making Mark kill his family and himself, implies that it is the spawn of Satan, and murders the psychic by making her vomit up her own innards.