When the three Grace children -- Mallory, Jared, and Simon -- and their mom move into Aunt Lucinda's old house, readers know there's magic afoot. The kids uncover a nest of assembled junk, and on a visit to the secret library via the dumbwaiter, Jared finds a note describing "my secret to all mankind." After a few mysterious pranks that get blamed on Jared, the boy finally digs up the real prize: Arthur Spiderwick's Field Guide to the Fantastical World Around You. Fortunately enough, the kids meet one of the critters listed in the guide -- a brownie named Thimbletack -- who makes it all "real" and helps provide the book's suspenseful conclusion: "'Throw the book away, toss it in a fire. If you do not heed, you will draw their ire.'"