REUTERS

A dozen years later, James Cameron has proven his point: He is king of the world.

As commander-in-chief of an army of visual-effects technicians, creature designers, motion-capture mavens, stunt performers, dancers, actors, music and sound magicians, he brings science-fiction movies into the 21st century with the jaw-dropping wonder that is Avatar. And he did it almost from scratch.

There is no underlining novel or myth to generate his story. He certainly draws deeply on Westerns, going back to The Vanishing American and, in particular, Dances With Wolves. And the American tragedy in Vietnam informs much of his story. But then all great stories build on the past.

After writing this story many years ago, he discovered that the technology he needed to make it happen did not exist. So, he went out and created it in collaboration with the best effects minds in the business. This is motion capture brought to a new high where every detail of the actors' performances gets preserved in the final CG character as they appear on the screen. Yes, those eyes are no longer dead holes but big and expressive, almost dominating the wide and long alien faces.

The movie is 161 minutes and flies by in a rush. Repeat business? You bet. Titanic-level business? That level may never be reached again, but after the film's December 18 release, 20th Century Fox will see more than enough grosses worldwide to cover its bet on Cameron.

But let's cut to the chase: A fully believable, flesh-and-blood (albeit not human flesh and blood) romance is the beating heart of Avatar. Cameron has never made a movie just to show off visual pyrotechnics: Every bit of technology in Avatar serves the greater purpose of a deeply felt love story.

The story takes place in 2154, three decades after a multinational corporation has established a mining colony on Pandora, a planet light years from Earth. A toxic environment and hostile natives -- one corporate apparatchik calls the locals blue monkeys -- forces the conglom to engage with Pandora by proxy. Humans dwell in oxygen-drenched cocoons but move out into mines or to confront the planet's hostile creatures in hugely fortified armor and robotics -- or as avatars.

The protagonist, Jake Sully (Sam Worthington), is a disabled former Marine who takes his late twin brother's place in the avatar program, a sort of bone thrown to the scientific community by the corporation in hopes that the study of Pandora and its population might create a more peaceful planet.

Without any training, Jake suddenly must learn how to link his consciousness to an avatar, a remotely controlled biological body that mixes human DNA with that of the native population, the Na'vi. Since he is incautious and overly curious, he immediately rushes into the fresh air -- fresh to a native, that is -- to throw open Pandora's many boxes.

What a glory Cameron has created for Jake to romp in, all in a crisp 3D realism. It's every fairy tale about flying dragons, magic plants, weirdly hypnotic creepy-crawlies and feral dogs rolled up into a rain forest with a highly advanced spiritual design. It seems -- although the scientists led by Sigourney Weaver's top doc have barely scratched the surface -- that a flow of energy ripples through the roots of trees and the spores of the plants, which the Na'vi know how to tap into.

The center of life is a holy tree where tribal memories and the wisdom of their ancestors is theirs for the asking. It grows in land the humans want to strip mine.

Jake manages to get taken in by one tribe where a powerful, Amazonian named Neytiri (Zoe Saldana) takes him under her wing to teach him how to live in the forest, speak the language and honor the traditions of nature. Yes, they fall in love, but Cameron has never been a sentimentalist: He makes it tough on his love birds. They must overcome obstacles and learn each other's heart.

In his months with the Na'vi, Jake experiences their life as the true world and that inside his crippled body locked in a coffin-like transponding devise, where he can control his avatar, as the dream. The switch to the other side is gradual, for his body remains with the human colony while his consciousness is sometimes elsewhere.

He provides solid intelligence about the Na'vi defensive capabilities to Col. Miles Quaritch (Stephen Lang), the ramrod head of security for the mining consortium and the movie's villain. But as Jake comes to see things through Neytiri's eyes, he hopes to establish enough trust between the humans and the natives to negotiate a peace. But the corporation wants the land the Na'vi occupy for its valuable raw material, so the colonel sees no purpose in this.

The battle for Pandora occupies much of the final third of the film. The planet's animal life -- the creatures of the ground and air -- give battle along with the Na'vi, but they come up against projectiles, bombs and armor that seemingly will be their ruin.

As with everything in Avatar, Cameron has coolly thought things through. With every visual tool he can muster, he takes viewers through the battle like a master tactician, demonstrating how every turn in the fight, every valiant death or cowardly act, changes its course. The screen is alive with more action and the soundtrack pops with more robust music than any dozen sci-fi shoot-'em-ups you care to mention.

After years of development and four years of production, no detail in the pic is unimportant. Cameron's collaborators excel, beginning with the actors. Whether in human shape or as natives, they all bring terrific vitality to their roles.

Mauro Fiore's cinematography is dazzling as it melts all the visual elements into a science fiction whole. You believe in Pandora. Rick Carter and Robert Stromberg's design brings Cameron's screenplay to life with disarming ease.

James Horner's score never intrudes but subtly eggs the action on, while the editing attributed to Cameron, Stephen Rivkin and John Refoua maintains a breathless pace that exhilarates rather than fatigues. Not a minute is wasted; there is no down time.

The only question is: How will Cameron ever top this?

Pandora