After being compelled to retire prematurely due to a debilitating illness, ex-baseball player Ray Waller relocates to a new home with his wife and two kids. He anticipates that the swimming pool in the backyard will offer enjoyment for the children and serve as a means of physical therapy for him. However, a sinister secret buried in the house’s history soon releases an evil force, plunging the family into a terrifying ordeal from which there seems to be no escape.