A struggling family, the Navratils, move into a new home after Beth's past drug addiction and its aftermath. Their young daughter Meg suffers a traumatic accident and develops separation anxiety, causing tension between Beth and her husband Jack. As Meg's behavior becomes more erratic, Beth becomes increasingly paranoid, suspecting something sinister is happening. She's haunted by nightmarish visions of parasitic creatures and is soon consumed by emotional dependency, self-destruction, and maternal sacrifice.