John James, a newly divorced father, moves into a rural South Carolina home with his adolescent daughter, Louisa, and young son, Sam. When Louisa begins to behave in strange new ways, John must uncover the truth behind her bizarre and increasingly violent transformation. Is the mysterious mound in their backyard connected to a former owner's shocking secret? And how far will a father go to protect his daughter from an ancient evil determined to take over her mind and body?