This vengeful "boggart" (the voice of Martin Short) turns into rat-size, foppish ``brownie''. For the last 80 years, Thimbletack has protected a field guide to magical creatures assembled by the Grace kids' Great Uncle Arthur Spiderwick (David Strathairn), who unlocked every secret before a silken cloud of fairies whisked him away forever. This book will Bring About the End of the World if it falls into the hands of Mulgarath, a truly evil ogre (voiced by Nick Nolte).

Then things go really sideways.

Director Mark Waters ("Mean Girls") creates an air of portent but also of adventure, which frees it from the overblown quality that bogs down some of the fantasy stories of late. There's no deep symbolism or hidden meaning in "Spiderwick"; just a truckload of scares and a couple of thrills, but as a swashbuckler for youngsters it’s colorful, and, every now and then, genuinely magical.