In 2154, the RDA corporation is mining Pandora, a lush, Earth-like moon of the planet Polyphemus, in the Alpha Centauri star system. Parker Selfridge (Giovanni Ribisi) heads the mining operation, which employs U.S. Marines for security. The corporation intends to exploit Pandora's reserves of a valuable mineral called unobtanium. Pandora is inhabited by the Na'vi, a blue-skinned species of sapient humanoids with feline characteristics. Physically much stronger and taller than humans, the Na'vi live in harmony with nature, worshiping a mother goddess called Eywa.
Pandora's atmosphere is toxic to humans, necessitating the use of breathing masks. Attempting to improve relations with the natives and learn about Pandora's biology, scientists grow Na'vi bodies modified with human DNA, called avatars, that are controlled by genetically matched, mentally linked human operators.] Jake Sully (Sam Worthington), a paraplegic former marine, replaces his murdered identical twin brother, a scientist trained to be an avatar operator. Doctor Grace Augustine (Sigourney Weaver), the head of the Avatar Program, considers Sully an inadequate replacement for his brother and relegates him to a bodyguard role.
In their avatar forms, Jake escorts Augustine and biologist Norm Spellman (Joel David Moore) into the jungle on a mission to reestablish relations with the Na'vi and end the threat of violence. A predator attacks the group and Jake becomes separated and lost. Forced to survive the night in Pandora's dangerous jungles, he is rescued by Neytiri (Zoe Saldana), a female Na'vi. Neytiri brings Jake to Hometree, which is inhabited by her clan, the Omaticaya. Mo'at (C. C. H. Pounder), a shaman and Neytiri's mother, shows interest in the warrior "Dream-walker", and instructs her daughter to teach Jake their ways. Colonel Miles Quaritch (Stephen Lang), leader of the security forces, enlists Jake to bring him intelligence about the natives that could help RDA negotiate with the Na'vi for...