Ten years after the events of Avatar, the human Jake Sully (Sam Worthington) is the chief of the Na’vi Omaticaya tribe and lives with Neytiri (Zoe Saldana), his sons Netayam (Jamie Foster) and Lo’ak (Brian Dalton), and his daughter Tuk (Trinity Jo-Li Bliss). Also, Kiri (Sigourney Weaver), who was born of the Na’vi avatar of human scientist Grace Augustine, and a human boy named Spider (Jack Champion), the son of Colonel Miles Quarritch, the main bad guy in Avatar. The humans are back like a bad penny, intending to terraform Pandora because they ruined their own planet. They build a base called Bridgehead City and bring some recombinant Na’vi avatars with the memories of dead RDA Marines, including the reborn dead Quarritch (Stephen Lang), who is out for revenge.
Jake launches a guerilla campaign against the RDA supply lines and Quarritch launches a counter-insurgency campaign against Jake, capturing his children. Jake and Neytiri rescue most of them, but Quarritch recognizes Spider as his son and decides to turn him. Spider decides to educate his father in Na’vi culture. Jake takes his family away from the Omaticaya region to the Metkayina reef-people clan of Pandora’s eastern seaboard. Some of the tribesman call them demons because of their human blood but the others willingly shelter them. As the family learns how to be reef people, Kiri falls in love with the sea and its creatures and Lo-ak bonds with Tsireya (Bailey Bass), the daughter of clan chief Tonowari (Cliff Curtis) and his wife Ronal (Kate Winslet).
Lo’ak is involved in a fight with Tsireya’s brother Aonung (Filip Geljo), whose friends strand him in the territory of a dangerous sea predator. Lo’ak is saved by Payakan, an intelligent Tulkun cetacean, who is an outcast because he was blamed for deaths among his species, though it was really human whalers responsible.. Kiri travels to link with the Metkayina’s tribe of souls but suffers a seizure. She is healed by Ronal, but Jake calls on friendly humans Norm Spellman (Joel David Moore) and Max Patel (Dileep Rao), and Quarritch is able to track them. Bringing Spider with him, he commandeers a whaling vessel. He brutally questions the natives and orders the whalers to slaughter the innocent Tulkuns.
The Metkayina learn of the slaughter and Lo’ak takes off to warn Payakan, along with Tsireya and Aonung. Lo’ak, Kitsiraya, and Tuk are captured by Quarritch and the rest of the family set out to save them. Jake is forced to surrender to Quarritch, but an angry Payakan attacks the whalers. Most of the crew are killed and the vessel is sunk. Netayam rescues Lo’ak, Tsiraya, and Spider, but is fatally shot. Jake and Quarritch face off and the latter uses Kiri as a hostage. Neytiri does the same with Spider and Quarritch stands down.
Jake, Quarritch, Neytiri, and Tuk are trapped inside the sinking vessel. Jake strangles Quarritch until he is unconscious and is rescued by Lo’ak and Payakan. Kiri summons sea creatures to save Neytiri and Tuk. Spider saves his father Quarritch but denounces him. After Netayam’s funeral, Jake decides to leave the Metkaina, but Tonowari welcomes him into the clan. The family decides to make a life in the sea and to keep on fighting the human invaders.
The film, of course, was directed by James Cameron from a screenplay written by him and Amanda Silver, with the help of Josh Friedman and Shane Salerno. It is a sequel to Avatar (2009) and there will be more. A third film is already begun. It was well received by critics, who praised the writing and technological marvels but criticized the length and what they called a thin narrative. Cinematographer Russell Carpenter had worked with Cameron on True Lies and Titanic. Most of the cast trained with free diver Kirk Krack in holding their breath underwater and Kate Winslet was the best at more than seven minutes. Avatar composer James Horner was killed in a plane crash in 2015, so the music was written by Simon Franglen, who had worked on music for Titanic, Avatar, and 2016’s The Magnificent Seven.
Criticized for the three-hour and 17-minute length of the movie, Cameron said he didn’t want to hear whining about length from people who binge-watch TV for eight hours. The Metkayina Clan was inspired by the Maori, so Maori actors, Maori dances, and Maori tattoos are front and center. As usual, Cameron started making the movie and then invented the necessary technology, like how to do performance capture underwater. Infrared radiation is used in the process, but infrared is absorbed by water, so they created a way to do it with ultraviolet. It kind of doesn’t matter what reviewers say. It will still be seen by thousands of people and there will be sequels, because the film is simply grand and gorgeous to watch, is basically all about love, and Cameron is the pre-eminent world-builder in cinema.