Freddie Highmore stars as a boy who begins to encounter strange creatures after his family inherits a remote house in The

Sarah Bolger, left, and Freddie Highmore star in The

Somewhere on Harry Potter’s quest for the One Ring, the golden compass has led us astray. The rules changed. Fantasy films became all about the blockbuster, sequels, mountains of merchandise, all sold to a ready-made fan base, fans who, often as not, weren’t the children these stories were originally intended for. These fans seem more worried about “franchise” than fun.

“The Spiderwick Chronicles” is a lighthearted contrast to all those fantasies freighted with the fate of the “human world,” movies toting the weight of this or that studio’s stock value. A top-drawer cast, sympathetic script (indie icon John Sayles did a draft or three), a director known for delicious teen edge and one of the great cinematographers of our time have conjured up a topical, whimsical and occasionally magical action-romp through a world we know, but don’t fully see.

Best of all, “Spiderwick” embraces its childishness, even if the fate of the “human world” is at stake.

A depressed, newly single mom (Mary Louise-Parker) drags her three kids to an inherited home in the boondocks, “the house that time forgot,” “that smells like old people,” her twins, Simon and Jared (Freddie Highmore), complain. There are skittering sounds inside the walls. Their “nut job” aunt has filled the pantries with salt, oatmeal, honey and tomato sauce, and salt is piled on every window sill.

Simon, the bookish twin, isn’t any more curious about this than Mom or sister Mallory (Sarah Bolger). But Jared, the twin with anger issues, is intrigued. He’s the one who gets a peek at the elves, fairies, goblins and hobgoblins that were their great uncle’s obsession. He’s the one who finds the “Field Guide” to these creatures that Uncle Arthur Spiderwick (David Strathairn) spent his life compiling.

And he’s the one the goblins (murderous, piglike beasties) and their ogre master Mulgrath (Nick Nolte) go after. Apparently Spiderwick’s “Field Guide” contains truths, spells and potions so dire that the shape-shifting Mulgrath could wipe out the fairy world, and then the real one. And the grown-ups can’t see any of this coming. They can’t see anything at all.

Director Mark Waters (“Mean Girls,” “Freaky Friday”) scores first by grounding these kids firmly in reality. Parker makes their family crisis obvious without having to spell things out. The parents have split, one child doesn’t know why and they’re all acting out. Kids in Waters’ movies act talk like real-world children. Jared’s first reaction at seeing his first hobgoblin?

“What the” h-e double fishsticks.

Waters landed “Knocked-Up’s” Seth Rogen to voice a slovenly bird-eating hobgoblin and Martin Short to rhyme and natter his way through the role of the “brownie,” Thimbletack.

“You die. I die. We all die. Bye-bye.”

The books this is based on skew younger than the Harry Potter novels, but they have a dense fantasy texture all their own. Everything in auntie’s pantry has a use, every bit of obvious foreshadowing (Mallory is a fencing champion) has a pay-off.

There are too many critters to keep track of, and for all the emotion packed into the family scenes, little of that transfers to the fantasy sequences. It’s not remotely as deep or as heavy as the “Potter” or “Lord of the Rings” or “Narnia” movies. But “The Spiderwick Chronicles” has sight gags and chases aplenty, and stuff scary enough to spook the 8- to 12-year-old in your house. Maybe it’ll even send them to the library, looking for their own “Field Guides” to Uncle Spiderwick’s world.