For those that are interested! Here is a review of the original scriptment for Avatar that is years old. Remember this will obviously have changed by now, but it does color the film somewhat. Enjoy!
We begin on planet Earth a hundred years hence, and it's pretty depressing. The planet's ecosystem has been so exploited by humankind that it can barely even shelter us any longer. Stripmining, air pollution, and every other form of exploitation and abuse have lead to mankind living in a tired world. "A cross between THX-1138 and a Calcutta train station," says the scriptment.
Because we've used up all Earth's resources (and apparently recycling techniques haven't advanced much) many companies are looking to the rest of the galaxy for new resources, and there's no extraterrestrial locale richer in resources than Pandora. Sure, pillaging Pandora has its problems (it's five light-years away and its atmosphere is toxic for humans to breathe) but its billions and billions of dollars worth of a (fictitious) superconducter called unobatainium make those hurdles well worth jumping over. There's a joint-venture of companies called the RDA who have a massive colony on Pandora to mine for unobtainium, as well as Pandora's many other resources.
Josh Sully (mid-twenties), is a disllusioned war vet, paralyzed from some meaningless war a few years back. (Spinal medicine apparently hasn't advanced much, either. Like much of science fiction - including even Star Trek - Avatar is frustratingly selective about how and where our technology has advanced.) Because he happens to have genes which are useful to the RDA, Josh ultimately finds himself making the three-year trip to Pandora to work on the Avatar program.
Pandora's most sentient race is called the Na'vi, and the RDA has a way to communicate with them. They grow Na'vi bodies and then those bodies are controlled externally by, well, "controllers". The controllers wear a headset called the link, and their human bodies are effectively unconscious while commandeering their Na'vi avatar. (Only a small percentage of humans have genes which allow for an Avatar body to be grown for them, and Josh is needed because he's in the minority.)
So Josh and the new crew from Earth awaken from suspended animation and arrive at the RDA's Pandora colony. It's run by Selfridge, an efficient company man wholly dedicated to the RDA. He also oversees the compound's massive, highly-trained military force, SECFOR, which is run mostly by Colonel Quaritch, a military man through-and-through who loves blood and hates life....especially Pandoran life.
Josh also meets Grace, who is both an Avatar and the compound's "xenobotanist". After he defends himself against her cynicism and insults, Grace takes to Josh and eventually becomes his mentor. (In the film, Grace will be the head of the entire Avatar program.)
So Josh begins life as a Na'vi. Their bodies are very human-like - they're bipedal and with similar faces - but they're blue, 10-feet tall, and evoke a feline impression, complete with a tail. Also, the Na'vi are much stronger, faster, and more agile than humans. At first, Josh is just happy to be walking again.
The Avatar program is just a small part of the RDA's Pandoran operation, there's a palpable tension between those in the Avatar program and everybody else. While most of the people at Hell's Gate (the RDA compound) are just mindless labor or system-dependant troops, the Avatar controllers are described sort of like a pack of stoners, high on the experience of living as a Na'vi. Says the scriptment, "They are a scruffy, smelly lot...with unkempt hair and beards and poor appetites."
When you put these two types of people together....something's bound to snap.
During an early venture into the beautiful but ultra-lethal Pandoran wilderness, one of the trigger-happy troops is about to fire at Grace's Avatar. Josh, now comfortable in his Avatar body, manhandles the troop (like a "ragdoll") and this doesn't exactly help in easing the tension between the two groups.
Later, on a seperate venture into Pandora, Josh gets seperated from the rest of the Avatars and finds himself having to fend for himself in the ultra-savage Pandoran wilderness. This is like putting a three year-old out in the middle of the worst jungles of Africa and expecting him to survive. The only way to survive in Pandora is knowledge, and Josh is still a novice.
But he's brave. After witnessing a manticore ("This thing could eat a T-Rex and have the Alien for dessert") scarf down a titanothere (like a rhino, only bigger and faster), Josh is then attacked by a pack of viperwolves ("Wolves as painted by Francis Bacon") and is saved by somebody who has a lot of knowledge of Pandora: Zuleika, the princess of the local Na'vi tribe. (How does she look? Well, when was the last time you saw an ugly princess in a Hollywood movie?)
Like Grace, Josh gets through Zuleika's tough exterior because she's inspired by his bravery and feistiness.
So Zuleika takes Josh back to her village, showing him the infinite mysteries of the Pandoran ecosystem. (It's like listening to a Greenpeace fanatic talk about Earth.) Josh meets the tribe, including Zuleika's parents, and begins the spiritual transformation from human to Na'vi. He feels "right" as a Na'vi.
(The scriptment makes clear in numerous places that the Na'vi are analogs for the Native Americans and their culture emobodies all of the traits that we descendants of European Christendom most romanticize about the Native Americans: a close community, a connection to the spiritual world, and, most of all, harmony with nature. And in Pandora, the spirtual world and nature are synonymous.
(In keeping with this analogy, the RDA is openly modeled after the European settlers.)
In the following days, Josh and Zuleika's bond grows and there's an elaborate montage of Josh fully learning the ways of the Na'vi and how to surivive in Pandora. He's a natural amongst them, and far more intuitive than the other science-minded Avatars. And more courageous, too.
Because of this, Josh is the first Avatar that the Na'vi invite into their ritualistic sturmbeest hunt (i.e., a buffalo hunt squared). This is where the important concept of "queueing" comes into play. Most Pandoran creatures have an external nerve which acts as an input port to their brains. The Na'vi have the output, called their queue, which enables them to jack into the animals and commandeer them. (The Na'vi queue looks like a ponytail, with the hair being functional nerves.)
After the sturmbeest hunt (where Josh again proves his courageous mettle), he partakes in the Na'vi's festive celebration. Afterwards, Zuleika takes Josh to her special place in the forest and they make love.
The next day, the real trouble begins. Selfridge unexpectedly bulldozes a large section of the Na'vi forest, including sacred land. Josh and Grace, in human form, argue against this new construction, especially in light of the new potential Josh's bonding with the Na'vi has created. But Selfridge and the troops are sick of the Avatar program (presumably jealous of them), and the bulldozing continues the next day. This time, Powersuit-armed troops accompany the bulldozers, killing anything that moves. Powersuits, as their name suggests, are massive robotic soots that dramatically improve the troops size, speed, strength, etc.
Josh realizes that there's no reasoning with Selfridge or the system-worshipping troops and bureaucrats beneath him, so he seeks assistance from his fellow controllers, trying to arrange some sort of coup. "Pandora is not Hell, it's Eden. And Eden is being bulldozed and stripmined and raped. We have no right. We are the aliens here. We are the space monsters".
The Avatar controllers might have free minds but, alas, they're non-committal.
That's cool. Because it's not like the Na'vi were responding to the foreign aggression with sing-ins and picket signs. Led by Tsu Te, their greatest warrior, the Na'vi sabotage the RDA's construction equipment, destroying it with a napalm-like incendiary.
The next day Selfridge orders a retaliatory raid and Quaritch and his troops love it. They hop into their powersuits and raid the Na'vi with an assault that makes Haditha or My Lai look like a schoolyard scuffle. Countless Na'vi are killed, including the tribe's patriach (Zuleika's father), and many others are taken prisoner....including Zuleika.
Selfridge has also shut down the Avatar program, physically turning off the link equipment. But Josh, Grace, and several others head to Site 26, an auxiliary link facility. On the way, Grace takes a bullet, and her human body ultimately dies.
After re-linking to his Avatar, Josh goes to the Na'vi and helps them orchestrate a rescue of their imprisoned friends. (There's nothing especially clever about this rescue: they get in under cover of the RDA's tractors and protect themselves from the automated sentry guns by wearing employee's identifying badges.)
As the Na'vi are fleeing the facility, Quaritch and the rest of the troops discover what's happened and they Powersuit up and chase the Na'vi into the forest. The Na'vi, though, utterly destroy the troops, killing many of them brutally. Quaritch, the bloodthirsty trooper, is left dumbstruck at the defeat of his team. "What the hell is happening. They just go their asses kicked by bows and arrows?"
This episode prompts a formal declaration of war from Selfridge: the Na'vi are all to be killed, as are the renegade controllers.
And Josh is rallying the Na'vi with no less enthusiasm. He gives his best Henry V speech. Here's an excerpt:
"He tells them they are not just fighting for this part of the forest or these few trees, but for the very future of their world. He says the history [of the humans]....is one of blood. For as long as can be remembered, they take what is not theirs.... Their world, their forest, is a dying place. A poisoned place. They have killed their mother. And they will do the same here. They must be driven away. When they come again they will come with all their force, and we must be ready. We must fight, to our last breath...."
After speech, Grace's Na'vi body miraculously appears. (Her human body had been killed, remember.) Grace, now living exclusively as a Na'vi, explains the wholistic wonders of the Pandoran ecosystem. Pandora, the planet itself, is essentially a brain, its tress are the neurons, their roots its synapses. The humans and their troops were a cancer for Pandora, and so it used its resources (the animal and the plants) to cleanse itself of the cancer. Lastly (and this will be important later), Pandora can sometimes do a "soul transfer", put one consciousness into another body (where the Na'vi keep their spare bodies, I don't know), and it chose to save Grace's soul in this manner.
Josh then has all the Na'vi queue into the planet itself so that he can explain to Pandora the magnitude of the danger the humans present. He tells her about the Navajo and the Sioux, and how their treaties and their trust was betrayed, as will Pandora be betrayed if she trusts the humans.
The next day, Selfridge and Quaritch begin the epic war that will later be called the Battle of the Big Rock Candy Mountain.
The first part of the battle is in the air between thousands of queued Na'vi riding bansheerays and leonyptertyx (savage, hawk-like predators with wingspans of perhaps 30 meters) against dozens of humans vehicles, which all have VTOL ability. Most of the human ships are destroyed in a hydrogen explosion when a massive hydrogen-based bug is detonated.
While the air battle rages, dozens of troops in Powersuits raid the forest, as well. Here, the Na'vi have the help of all of Pandora's creatures, which the planet has directed against the humans.
Now these two interconnected battles are too dense with events for me to explain here. Suffice to say, the Pandorans eventually come ou ton top.
The battle climaxes in a fight between Josh (as a Na'vi, of course) fighting Colonel Quaritch in a Powersuit. Josh eventually gets Quaritch out of the suit. Quaritch flees back to the base on foot but is chased down by a pack of viperwolves.
And that's it for the Battle of the Big Rock Candy Mountain.
All the surviving humans are rounded up - including Selfridge - and shipped back to the command ship in Pandora's orbit. Josh bluffs to them that Pandora is developing an extremely potent antibody for humans in its atmosphere, and if they return they will all certainly die.
That night, the Na'vi gather in a chant, queued into the planet itself. Josh's human and Avatar bodies lie side by side. His rebreather is removed from his human body, insuring its death. Zuleika kisses him....and his Na'vi eyes open."
Text in green above from David Brennan.