A single mother moves her three children into the infamous Amityville house, desperate for a fresh start and hopeful that the change will aid in the recovery of her comatose son, James. The family is unaware of the home's dark past, that it is the site of a notorious mass murder where a young man killed his family, claiming he was driven to it by malevolent forces within the house. As they settle in, strange incidents begin to unfold, suggesting that the house's sinister history is far from over.

The eldest daughter, Belle, quickly realizes that something is amiss with their new home. Her suspicions grow as she witnesses unexplained phenomena and her brother James's health begins to miracously improve in inexplicable ways. Belle's investigations lead her to discover the horrifying truth about the house's past. She finds herself in a desperate struggle to save her family from the malevolent forces that have latched onto them, realizing that they may be dealing with a darkness beyond their understanding.