I'm the King of the Castle

Thomas (Régis Arpin) is the 12-year-old son of a millionaire who lives in a big mansion surrounded by woods in France. When his mother dies, his father hires a widow maid to take care of all while he is away. The woman brings her only son, Charles, to live with them and, hopefully, make company to lonesome Thomas. The rich boy and the poor one become enemies from the very first encounter. Moved essentially by jealousy and fear, Thomas decides to turn Charles' life into hell, especially after their parents eventually fall in love.