Carmen, Patrick. The Dark Hills divide [Land of Elyon Bk I]

Carmen, Patrick. The Dark Hills divide [Land of Elyon Bk I]. Scholastic, 2005 [0-439-70093-0]
Alexa lives in a world of walled cities with walled roads between them. Every summer she visits Bridewell with her father where she explores the city and the lodge where they stay. One day she finds a way to get outside the wall where she meets a world of creatures which she can understand and befriends them. She finds out from them that some outlaws will invade the city with the help of a spy in the city. When she gets back in the city she tracks down some mysteries and takes her findings to the ruling council still not knowing who the inside spy is. This 250 page book is a mystery, adventure, and fantasy which is a good read. Unfortunately it has a juvenile illustration on the cover which may turn off some kids.