In a seemingly idyllic small town, Christine Penmark lives with her young daughter, Rhoda, who appears to be the epitome of sweetness and perfection. However, when one of Rhoda's classmates, Claude Daigle, dies under mysterious circumstances during a school picnic, Christine begins to notice unsettling behavior in her daughter. Rhoda's charm and politeness start to seem more like a facade hiding darker tendencies. Discussions with family and friends, especially with Christine's father, reveal disturbing details about Rhoda's aggressive and manipulative interactions. The family's gardener, LeRoy, also starts to see through Rhoda's angelic pretense, sensing something malevolent beneath her façade.

As Christine delves deeper into the events surrounding Claude's death, her own childhood and family history surface, leading to alarming discoveries about inherited traits and past crimes. Her growing dread and Rhoda's increasingly sinister behavior bring Christine to face the horrifying possibility that her daughter's innocence might be a mask for something much more malevolent. Amid conflicting emotions and a sense of impending doom, Christine's world unravels as she confronts the chilling reality of her daughter's true nature. The tension escalates, weaving a narrative of maternal anguish and moral complexity, leaving Christine grappling with decisions that could have permanent and devastating consequences for her family.