Noah Ringer is the heroic Aung in M. Night Shyamalan’s action fantasy The Last Airbender. (Industrial Light & Magic/Paramount Pictures)

Devotees of the terrific Nickelodeon cartoon series Avatar: The Last Airbender were understandably concerned over M. Night Shyamalan's decision to make his film adaptation of the Eastern-influenced TV favourite with a predominantly white cast.

Incoherent and marred by amateurish performances and cruddy 3-D, The Last Airbender is a contender for feel-bad movie of the summer.

I'm here to tell those fans they needn't worry — racism is the least of the problems in Shyamalan's film. Muddy in appearance, short on coherent narrative, marred by amateurish performances and some of the cruddiest 3-D in recent memory, The Last Airbender is a contender for feel-bad movie of the summer.

The sheer awfulness of The Last Airbender is puzzling, given that Shyamalan's script is initially faithful to the source material. At the outset, clunky voice-over narration lays out the terrain established in the series' three-season run. The world consists of four nations, each based around an element (earth, air, fire and water). Special-powered humans known as "benders" can manipulate certain elements to their advantage, but there is only one special being, known as the Avatar, who can master all four elements, and thus help restore harmony to a world that is at war.

When a young water-bender named Katara (Nicola Peltz) and her brother Sokka (Jackson Rathbone) happen upon a tattoo-emblazoned youngster encased in some glowing Arctic ice, they suspect the boy, Aang (Noah Ringer), is likely the saviour they've been waiting for. If only!

What follows is less an adventure than a disjointed series of tedious events. Shyamalan moves his young trio through a series of settings and action sequences that certainly resemble an episode of the cartoon, only drained of all humour and joy. Katara helps Aang brush up on his water-bending skills; the exiled Prince Zuko (Dev Patel, doing his damndest to create a real character) wages war against the Avatar; an adorable flying bat lemur known as Momo makes an all-too brief appearance; and a precious water scroll is handed down. Characters like the white-haired Princess Yue (Seychelle Gabriel) pop up with nary an explanation, and the filmmaker races through plot points as though he were ticking off items on a grocery list.

Sokka (Jackson Rathbone, left) and Katara (Nicola Peltz) in a scene from The Last Airbender. (Zade Rosenthal/Paramount Pictures)

Perhaps sensing that this narrative could be tough to follow, Shyamalan sees to it that every scene in The Last Airbender features big chunks of exposition or flashbacks to the characters' traumatic backstories to keep viewers up to speed. This proves deadly for the young cast members, many of whom spout howlers like, "I will miss you more than you know." As Aang, Noah Ringer fares the worst. He's forced to endure New Age-y lectures about never going into battle until you've healed your wounded soul — all while keeping a straight face. It's no wonder the boy looks like a tormented, somnabulent Eddie Munster throughout.

This would all be excusable if The Last Airbender delivered in its action scenes, but they prove to be as muddled and murky as the plot. Waving his hands in swift martial arts movements, Aang mostly stirs up cloudy duststorms — and the movie's unnecessary conversion to 3-D only serves to make a lot of the characters' actions look fake and lifeless. Even the colour palette, which moves from dark blues to dreary charcoal by film's end, causes visibility issues and dampened morale.

Shyamalan fares better in the movie's epic long shots, especially one staged against the ornate, wintry palace that serves as home to the northern water tribe. Yet even this brief splendour is soured by the director's decision to cloud the frame with lots of poorly staged slow-mo high kicks and a real bummer of a tidal wave.

Shyamalan's previous work, the environmental-disaster movie The Happening (2008), was a box-office bomb that many critics felt was the worst film of his career. The Last Airbender may well trump that film in Shyamalan's bizarre race to the bottom.

The Last Airbender opens July 2.

Lee Ferguson writes about the arts for CBC News.