In this film, Rhoda "Bonnie" Penmark is a seemingly sweet and innocent little girl who, unbeknownst to her parents, is capable of extreme cruelty. She systematically murders her classmates and eventually, her siblings. Her father, played by William Hopper, finally realizes the horrifying truth about his daughter and is left devastated.
The movie explores themes of nature vs. nurture, innocence and evil, and the unsettling potential for darkness within human nature, particularly in children.