In 2154, humans have depleted the Earth's natural resources, leading the Resources Development Administration (RDA) to mine for a mineral called 'unobtanium' on the planet of Pandora. The planet, whose atmosphere is poisonous to humans, is inhabited by the Na'vi, who live in harmony with nature and worship the mother goddess Eywa. Jake Sully, a paraplegic veteran Marine, is used to operate an 'avatar', Na'vi-human hybrids, to explore Pandora's biosphere.
Jake, along with scientists Grace Augustine and Norm Spellman, operate their avatars and explore Pandora. While collecting biological data, Jake's avatar meets Neytiri, a Na'vi and the daughter of her tribe's chief, Eytukan. Neytiri's mother, Mo'at, instructs Neytiri to initiate Jake into their society. Colonel Miles Quaritch, the head of RDA's mining operation, promises to restore Jake's legs if he gathers information on the Na'vi and the clan's gathering place, an aboreal called Hometree, which stands above a rich deposit of unobtanium. Learning of this, Grace transfers herself, Jake, and Norm into an outpost. Over the course of three months, Jake grows to sympathize with the Na'vi. After being initiated into the tribe, he and Neytiri choose each other as mates. When Jake attempts to disable a bulldozer threatening to destroy a sacred Na'vi site, administrator Parker Selfridge orders Hometree destroyed.
The RDA give Jake and Grace one hour to evacuate the Na'vi before they destroy Hometree. However, the Na'vi refuse to listen and take Jake and Grace prisoner. The RDA arrive and destroy Hometree, and Eytukan is killed, amongst many other Na'vi. Distraught, Neytiri drives Jake away, and he and Grace are detached from their avatars and imprisoned. However, one of the RDA pilots, Trudy Chacon, frees them and they flee, but during the escape, Grace is fatally wounded by Quaritch.
To regain the clan's trust, Jake connects his mind to Toruk, a creature honored by the Na'vi. At the sacred Tree of Souls, Jake pleads with Mo'at to heal Grace. The Na'vi attempt to transfer Grace from her human body into her avatar, but she dies before the process is complete. Jake, supported by the new clan leader Tsu'tey, rallies the Na'vi to battle against the RDA. On the eve of the battle, Jake prays to Eywa to intercede and aid the Na'vi. In the war that follows, Tsu'tey and Trudy are killed, but the RDA are overwhelmed when the Pandoran wildlife join the battle. Quaritch, wearing an AMP suit, battles Jake and Neytiri, breaking open the avatar link unit containing Jake's human body. However, Neytiri kills Quaritch and saves Jake from suffocation.
In the aftermath of the battle, all humans are expelled from Pandora and returned to Earth, with the exception of a select few humans. Jake is transferred into his avatar body permanently with the aid of the Tree of Souls.
- Sam Worthington as Jake Sully.
- Zoe Saldana as Neytiri.
- Sigourney Weaver as Grace Augustine.
- Stephen Lang as Colonel Miles Quaritch.
- Michelle Rodriguez as Trudy Chacon.
- Giovanni Ribisi as Parker Selfridge.
- Joe David Moore as Norm Spellman.
- CCH Pounder as Mo'at.
- Wes Studi as Eytukan.
- Laz Alonso as Tsu'tey.