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Can you crack the case with six clues or less?
Moon Hollow's town library is a favorite spot for the Mysterious Four. But when the strange, masonic glyphs that decorate the building prove to be a secret code, they discover there's more than books hidden away inside.
Embarking on a treasure hunt, Viola, Sylvester, Rosie, and Woodrow must run a gauntlet of mysteries and puzzles--and readers are invited to guess alongside them with every new clue they uncover.
Each book comes with an exclusive code so that readers can download a FREE copy of the e-book . . . which includes an extra mystery unavailable anywhere else!