In a small suburban town in the
Hudson Valley, 11-year-old genius Henry Carpenter and his younger brother Peter are being raised by their single mother Susan, a waitress who is working on writing children's books. Henry has used his intellect to invest successfully in the stock market, building up a very substantial nest egg for his family. He also protects Peter from a school bully and builds
Rube Goldberg machines in their treehouse. Henry and Susan are both fond of their next-door neighbor, Henry's classmate Christina Sickleman, who has recently become glum. Henry believes that he sees Christina being abused by her stepfather Glenn, the local police commissioner. He reports the abuse to
social services and the school principal, Janice Wilder, but Glenn has connections throughout the local government, and Wilder is reluctant to challenge the commissioner without "conclusive evidence". Henry is unable to get the authorities to launch a serious investigation that would protect Christina. Henry tells his mother that when someone is in trouble, those who can help must take action. He develops a detailed plan to rescue Christina that he details in a notebook. After a violent seizure, he is taken to the hospital, where he is diagnosed with a brain tumor and undergoes surgery. Anticipating his death, he tells Peter to give Susan the notebook. Days later, Henry dies. Susan is distraught at Henry's death and has difficulty functioning, but when Peter gives her the notebook, she focuses on Henry's plan. She tries unsuccessfully to interest a nearby social-services agency in opening an investigation. One night, from the boys' bedroom window, she sees Glenn in Christina's room and decides to carry out the plan. The notebook and an accompanying cassette tape describe Henry's step-by-step plan to kill Glenn with a sniper rifle while covering Susan's tracks so that tracing the murder back to her will be impossible. Her alibi is to be provided by executing the murder while Christina and Peter are performing at the school talent show. Susan slips away from the show, putting the plan into motion. As she is about to pull the trigger, she realizes that Henry's plan, though ingenious, is the construct of a child, and she must act as an adult. She immediately confronts Glenn and tells him that she will expose him for what he has done to Christina. He replies that everyone will believe him, not her, and tells her that he is going to call his police chief to come arrest her. At the same time, affected by Christina's dance performance at the talent show, Principal Wilder decides to follow through on the abuse accusation and contacts the authorities. Glenn returns home, calls his relative at Social Services, and learns that an investigation is being opened into his abuse of Christina. As the police arrive at his house, Glenn kills himself. Susan legally adopts Christina as her daughter. She also finishes writing one of her children's books, as Henry had urged her to do. == Cast ==