Who Stole the Wizard of Oz? — Avi

THIEF!
Becky is furious! The Checkertown librarian has accused her of stealing a rare children's book, and she's determined to prove her innocence by tracking down the real culprit. With the help of her twin brother Toby, Becky investigates a rash of other oddball crimes about town -- including the disappearance of four more children's books. The twins think they've hit pay dirt when they discover that clues to the mystery -- directions to a secret treasure -- can be found in the stories themselves. But can they piece together their elusive treasure map...before the real thief does?