Noted children's book author Madonna is about to embark on another kid-friendly project. According to the Hollywood Reporter, she'll make her cartoon debut in Arthur, an $80 million computer-animated feature due in 2006. It's the story of a 10-year-old boy who tries to save his grandfather's house from developers by embarking on a quest for hidden treasure in the land of the Minimoys, a race of tiny folk who live in harmony with nature. Madonna's role is Princess Selenia, who accompanies Arthur to a forbidden city where a villainous creature lives. The film is based on a series of children's books by Luc Besson, who will also direct the movie. We'd never have figured Besson, best known as the director and producer of hyper-violent films like La Femme Nikita, for a children's story author; we figured his idea of a story for kids was The Professional, the 1994 Besson movie that starred a pre-pubescent Natalie Portman as a little girl who bonds with a contract killer after corrupt cops massacre her family. Of course, a few years ago, we wouldn't have imagined that Madonna would turn her attention to kiddie lit either.