Soon after the Montelli family buys a house in the Long Island suburb of Amityville, unsettling events begin to occur. Mysterious demons seem to infest the house, preying on abusive father Anthony (Burt Young) and ferociously religious mother Dolores (Rutanya Alda), who calls on family priest Father Adamsky (James Olson) for an exorcism. Teenage Sonny (Jack Magner) is drawn furthest into madness, abusing his younger sister, Patricia (Diane Franklin), and eventually exploding in a horrific fury.