Mild-mannered apartment caretaker Cleveland Heep (Paul Giamatti) finds himself in a real-life bedtime story when he rescues a mystical "Lady in the Water" (Bryce Dallas Howard) from the swimming pool.

M. Night Shyamalan used to be a showman.

Sometimes it worked. ("Sixth Sense," anyone?) Sometimes it didn't. (Take "The Village" -- please.)

But whenever Shyamalan dipped into his bag of tricks, you knew you were in for a clever, if not always credible, cinematic ride.

As "Lady in the Water" proves, however, Shyamalan's tired of being a mere showman.

He now wants to be a shaman, a powerful conjurer capable of casting a magical spell over audiences.

Sorry, Mr. Shyamalan. Not this time.

Your kids may have been enthralled by the bedtime story you told them one night, about a mysterious creature living beneath your swimming pool. But whatever you told them doesn't hold water on the big screen.

More's the pity, because in times like these we could definitely use something to believe in. Something other than this pretentious, labored and oh so pedestrian journey into the imagination of someone who's not nearly as spellbinding as he thinks he is.

Which is not to say that "Lady in the Water" is entirely without merit. At least it boasts a cast full of wonderful actors -- plus the auteur himself, expanding his Alfred Hitchcock-style cameo appearances well beyond the point of diminishing returns.

Spin as he might, Shyamalan just can't transform this straw into gold.

Taking more than a page from Hitchcock (whom he clearly wants to emulate, judging by the number of show-offy overhead shots he throws in), Shyamalan focuses on an ordinary man in extraordinary circumstances: Cleveland Heep (Paul Giamatti, in yet another soulful performance overflowing with lovely, lonely anguish).

The stuttering superintendent of the Cove, a suburban Philadelphia apartment complex, Cleveland takes refuge -- from life and from his all-too-painful memories -- in his mundane job.

Until, late one night, Cleveland spots someone in the pool. Someone named Story ("The Village's" ethereal Bryce Dallas Howard), a mystical, nymph-like narf who's trying to return to her watery home -- if only those slavering, ravenous scrunts lurking beyond the apartment complex would stop menacing her.

Fortunately for Story, she's picked the right apartment complex to splash into. Not only does Cleveland believe Story's story, he's got a complex full of eccentrics destined to play pivotal roles in her rescue.

There's a student (sassy Cindy Cheung) who remembers her mother's bedtime stories about narfs and scrunts and eatlons. (Oh, my!) A loving father (Jeffrey Wright, wonderful as always) with a penchant for solving crossword puzzles. An animal fancier (Mary Beth Hurt) at ease with the nonhuman world. An aspiring change-the-world writer (Shyamalan) and his devoted sister (Sarita Choudhury). A bodybuilder (Freddy Rodriguez) with an unorthodox training regimen. A recluse (Bill Irwin) who rails against a hostile world.

My favorite (but of course) is the Cove's newest tenant: an arrogant movie and book critic (hilarious deadpan Bob Balaban) whose chilly cynicism marks him as a nonbeliever. And we all know what happens to people who won't believe stories about strange creatures lurking in the night, don't we, kids?

OK, so Shyamalan would like to put the bite on movie critics. That seems fair -- because this movie critic's definitely putting the bite on him.

Or, more precisely, on his movie's glacial pacing and monotonous camera moves. The recurring nightmare of the movie's slow, portentous pans made me want to shout, "Enough already! We get it! We get that you're trying to manufacture artificial scares because there aren't any real ones in this convoluted and contradictory script!"

Thankfully, a few ooga-booga, "gotcha" moments briefly pierce the torpor. But "Lady in the Water" never achieves the palpable sense of wonder that would lift it, and us, into the realm of the truly magical.

Movies like "The Wizard of Oz" and "E.T. the Extra-Terrestrial" -- two movies Shyamalan cites as favorites -- conjure such enchantment so easily that we can't help but dance along with Dorothy as we follow the Yellow Brick Road or ride shotgun with E.T. while Elliott pedals their bike into the sky.

And anyone who would dare compare "Lady in the Water" -- M. Night Shyamalan, that means you -- with the likes of "The Wizard of Oz" or "E.T." deserves to be chomped by a vicious scrunt.

As I don't believe in scrunts -- or anything else in "Lady in the Water," except the poor actors trying desperately to sell such preposterous claptrap -- I suppose Shyamalan will have to settle for another curmudgeonly critic giving him another negative review.