In “The Last Airbender,” writer-director M. Night Shyamalan takes the beloved Nickelodeon anime series — the full title was “Avatar: The Last Airbender” — and turns it into 103 minutes of overproduced, stilted nonsense.

Fans of the TV show, who are already well-versed in the complex mythology of this story about a war between the realms of the four elements, could conceivably enjoy seeing the series re-enacted in high-tech live-action. Early in the movie comes a brief battle between fire and earth benders — people with the gift to control their respective elements — that suggests all that exposition you’ve endured thus far may eventually build into something pretty cool. But the set-up never stops — characters are constantly explaining themselves and what they need to accomplish, instead of actually speaking to each other — and the plot doesn’t so much build as prattle.

The chief reason “The Last Airbender” doesn’t work is that this is the first chapter in a three-volume tale (the movie is subtitled “Book I: Water”), and once you realize the film is only going to take you to a preordained point in the story and end with a cliffhanger, the picture becomes an endurance test. Peter Jackson filmed all three “Lord of the Rings” movies back-to-back, so while watching “The Fellowship of the Ring,” you knew you weren’t going to get a complete ending, but you’d eventually see the entire epic.

Shyamalan has only directed one “Airbender” movie — he’s signed on for two sequels, but their fate rests with the box office grosses of this $150 million production — and this situation feels awfully reminiscent of “The Golden Compass,” the first (and open-ended) installment in an intended franchise that was abandoned after audiences didn’t turn out in enough numbers.

In compressing what took 10 hours to unfold on TV into one choppy, CGI-laden film, “The Last Airbender” retains its basic narrative but loses its soul. The eponymous hero Aang, a boy with great powers who must learn to bend water, fire and earth before bringing peace to the four realms, is played by Noah Ringer, a young actor who fares well with the elaborate action and interpretative-dance movements benders make while doing their magic.

But Ringer has zero personality or charm — he’s a pleasant but generic screen presence — and the characters surrounding him, such as his guardians Katara (Nicola Peltz) and Sokka (“Twilight’s” Jackson Rathbone), fare even worse. Shyamalan (“The Sixth Sense,” “The Village,” “The Happening”) has never directed this sort of gargantuan epic before, and he seems overwhelmed by the technical demands of the job, leaving the actors to fend for themselves, which they mostly do poorly.

The only character who makes any sort of impression is the Fire Prince Zuko (“Slumdog Millionaire’s” Dev Patel), who wants to kidnap Aang in order to win back his father’s love and respect. He’s a familiar but engaging archetype — the disgraced son on a quest to regain his family honor — and “The Last Airbender’s” best scenes all involve him.

The rest of the movie is composed of a giant flying buffalo, a wise dragon that talks in an old man’s voice and battle scenes that once again resort to the bullet-time photography “The Matrix” invented.

“The Last Airbender” may please children, who enjoy watching heroic kids kicking grown-up butts. But despite the originality and depth of the scenario, this feels like awfully silly, overblown nonsense (“Water teaches us acceptance. Let your emotions flow like water!”), saddled by a fuzzy 3D conversion that distracts more than it adds. The best movie fantasies are light and fast and transporting: If “The Last Airbender” were an element, it would be slushy, heavy mud.