‘Last Airbender’ lands with thud

There is incomprehensible, and there is inexplicable, and then there is “The Last Airbender,” M. Night Shyamalan’s adaptation of the popular Nickelodeon cartoon “Avatar: The Last Airbender.”

Not to be confused with James Cameron’s tale of tree-hugging blue people, this saga revolves around (I think) a war-torn future world waiting for a messiah to unite it.

But the screenplay (also by Shyamalan) is cluttered with so much gobbledygook exposition and confusing action that it’s impossible to grasp what’s supposed to be going on for more than 15 seconds at a stretch.

Who would have thought Shyamalan would come up with a movie that makes his “Lady in the Water” look positively sensible?

Actually, this seems to be the inevitable trajectory of a tremendously talented filmmaker who at some point convinced himself he could do no wrong. Just like “Lady in the Water,” “The Last Airbender” suggests an artist so completely lost inside his creation that he has no idea what works and what doesn’t.

As it turns out, nothing works here. The things Shyamalan once did so well, especially in “The Sixth Sense” and “Unbreakable” – perfectly modulating the rhythms of the scenes and patiently building tension – have entirely abandoned him.

The opening scenes introduce us to sister and brother Katara (Nicola Peltz) and Sokka (Jackson Rathbone), two members of Water Nation – one of four nations that were once kept in balance by the mysterious Avatar. But when the Avatar went missing, all hell broke loose, as the Fire Nation declared war on the others, including Air Nation and Earth Nation.

Got all that? (If not, there’s also a Yoda-like creature called “the spirit dragon” to confuse you even further.)

Part of the problem here is that Shyamalan has tried to cram about three seasons of the cartoon’s plot points into this one movie, including the story of the prince of Fire Nation (Dev Patel from “Slumdog Millionaire”), who was cast out of the palace for being a wimp.

The other, bigger problem is that you don’t care about any of these people, whose motivations and personalities are impossible to discern.

At some point, a savior emerges, Aang (Noah Ringer), a boy who can bend air – i.e., make the wind knock people over – and thus is the Avatar who will bring peace to this universe.

Sweeping his arms about him and prancing around the set, the bald, wide-eyed Aang spends a dismaying portion of the proceedings looking like he’s practicing tai-chi. By the time the (mystifying) climax rolls around, the movie has come to resemble an unwieldy hybrid of “Little Buddha” and “Crouching Tiger, Hidden Dragon.”

What else can one complain about? The cheesy effects; the 3-D photography that barely looks three-dimensional; the fact that none of the cute-looking but vastly inexperienced lead actors has the chops to be carrying a large production.

It’s a little early to be saying this, but I’d wager good money that you won’t see a worse movie this year.