Fantastic Mr. Fox is a book by Roald Dahl, probably most famous for his books Charlie and the Chocolate Factory and James and the Giant Peach. The book was released in 1970, and was just recently released as a movie.
Compared to some of Dahl's other children's books, this book is shorter, and more profusely illustrated. Even for an elementary school student, it would probably be something that could be read in one sitting. Whether the content is something that is appropriate for younger ages is something that is much more debatable. The action follows the titular Mr. Fox, who troubles three separate poultry farmers by stealing their poultry to feed his family. The farmers join together to hunt down Mr. Fox, first with guns and then by digging out his den. Mr. Fox escapes, and turns the tables on the farmers by digging into their storehouses, and lives happily ever after along with some of his other subterranean kin.
That is the plot. I am somewhat curious as to how they rounded this out into a movie. If there is substance to the book, it is not in the plot, but rather in the descriptions, which tend to be vivid and grotesque. However, once the descriptions of the villainous farmers are taken away, there is very little left to this book. The most disappointing part of this is that as a book featuring a fox, a traditional trickster figure, Mr. Fox isn't really that smart. He does dig up into the storehouses of the evil farmers, but that is hardly a coup of great wit and trickery.
So except for those who are attracted to books that have grotesque or sadistic treats, there is not much in this book. That it is written for children doesn't make up for the lack of plot or substance: it just makes the books cruel moments that much more unsettling.