In a small suburban town in the Hudson Valley, 11-year-old boy 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 picture books. Henry has used his intellect to invest successfully in the stock market, building up a very substantial nest egg for his family. Henry also protects Peter from a school bully and builds Rube Goldberg machines in their tree house. Henry and Susan are both fond of their next-door neighbor (and Henry's classmate), Christina Sickleman, who has recently become glum.