Avatar, James Cameron’s first movie since Titanic (1997), is a solid science fiction story, probably a classic. It is a visually stunning extravaganza which seems to have required the contributions of just about every CGI effects studio on this planet.

A lot of people are saying that while the movie is visually stunning the story is weak. I wouldn’t call it weak; I found it exciting and rather affecting. It is certainly very derivative and rather predictable, but that seems to be true of just about everything that comes out of Hollywood these days.

Pandora is a small but beautiful planet (actually a moon orbiting a gas giant.) It has less gravity than Earth and (judging from the flying creatures) a denser atmosphere. The natives are 20-foot-tall blue-skinned humanoids. They are noble savages who live in harmony with nature, yadda yadda yadda, you know the drill.

From Earth’s standpoint the most important thing about Pandora is its rich reserves of unobtainium. Long-time science fiction fans will remember that unobtainium is vital for anti-gravity devices, room-temperature superconductors and interstellar travel.

An interstellar corporation referred to only as “The Company” is charged with setting up a base on Pandora and extracting the unobtainium. It isn’t easy. The atmosphere is poisonous to humans, the jungles are full of huge animals that would just as soon eat you as look at you, and the natives have poisoned arrows. Even with aircraft and mechas (some of the best-looking mechas I have ever seen) the humans aren’t making much progress.

A team of scientists led by Dr. Grace Augustine (Sigourney Weaver) has been trying to explore Pandora and make friends with the natives by using “Avatars”, artificial genetically engineered bodies that look like the natives. Avatars are made with a mixture of human and native DNA; the human who contributed the genetic material can link to the Avatar body and remotely control it.

Jake Sully (Sam Worthington), a paraplegic ex-Marine, agrees to join the Avatar team as a replacement for his twin brother who was killed just before leaving for Pandora. (Because he is genetically identical, he is the only one who can use his brother’s Avatar.)

Grace is most displeased to get a new team member with no scientific training, but Colonel Miles Quaritch (Stephen Lang), the hard-assed security chief, is delighted. He thinks having a military man as a Avatar will allow him to gather the intelligence needed to put down the natives once and for all.

Jake soon gets lost in the jungle and meets a beautiful native named Neytiri (Zoe Saldana). Though contemptuous of his ignorance, she ends up becoming his mentor, teaching him how to survive in the jungle, ride huge flying beasts and commune with nature.

All of this is obviously derivative of dozens of movies about white men who get adopted into American Indian tribes. To me it also seems even more derivative of a much older tradition: the “John Carter of Mars” stories by Edgar Rice Burroughs.

The film has a mixture of obsessive, gritty realism and pulp fantasy not seen since the first Star Wars movie. As such it treads a dangerous line between being exciting and merely being absurd. At first I wasn’t sure which side of the line it was going to end up on, but by the midpoint I was totally caught up in it. Ultimately the most important thing about a movie is how entertaining it is, and this one is very entertaining.