James Cameron delivered box office gold for the second time in his life when he released Avatar in 2009. At the time, the number one movie of all time was Titanic, which was the last film Cameron made before Avatar. (Star Wars: The Force Awakens later overtook both of them at the domestic box office, but Avatar remains the all time #1 film worldwide.) After its release, Avatar changed cinema with an upgrade to digital 3D filmmaking and photo-realistic CGI characters and alien environments.

It was an obscenely expensive movie, but Cameron's track record gave him the freedom to go for it. And he was vindicated a second time. In an age when a movie is made or undone purely by its opening weekend, Cameron has an amazing capacity for making movies with staying power at the box office. Week after week, audiences poured into theaters to watch Cameron's dazzling vision of an alien world.

After eight long years, Avatar 2 has at long last kicked off production. What can we expect from the sequel? What's the story? Who's back? And just how many sequels are we talking about? Here's every detail we know.

Avatar 2 Returning Cast Members

Lead actors Sam Worthington and Zoe Saldana are both back, as alien lovebirds Jake Sully and Neytiri, respectively. Their romance formed the backbone of the first film, so don't be surprised if they have a child or two now after several years together.

Also back is Sigourney Weaver, despite her character's death in the first movie. Weaver told interviewers a while back that she was playing a new character, but Cameron later said that her original character will somehow be alive again. Death seems to have little meaning on Pandora, because she's not the only deceased character returning to a major role. Stephen Lang's villain Miles Quaritch is back, too, and Cameron has confirmed he'll be the antagonist in all of the Avatar sequels. (More on that later.) Lang, by the way, at 65 years old, is still as fit and buff as ever.

CCH Pounder returns as Neytiri's mother and the tribe's spiritual leader, Mo'at. Joel David Moore reprises his good guy scientist Norm Spellman. And Matt Gerald is back as Quaritch's subordinate, Lyle Wainfleet. Wainfleet is yet another character that died in Avatar but will somehow return for the sequels.

Avatar 2 New Cast Members

Cliff Curtis, best known for his work on Fear the Walking Dead, has signed on for a major role. Curtis will play Tonowari, another motion-captured Na'vi character. Tonowari is the leader of the Metkayina Clan, a tribe of Na'vi reef dwellers.

Oona Chaplin is remembered best as Robb Stark's doomed, pregnant bride Talisa on Game of Thrones, though like Curtis, she's had many other roles. She joins the cast in Avatar 2 as a mystery character named Varang. Nothing has yet been revealed about Varang, leading to speculation that she could be Jake and Neytiri's daughter. Especially since the Sully kids and grandkids may play a major part in the saga. (Keep reading for more on the Sully family.)

Avatar 2's Plot

Based on comments from various sources, Avatar 2 is expected to be set at least eight years after the first movie. Early on, James Cameron told journalists that his sequels would "widen the universe," expanding to other moons of Polyphemus, the planet Pandora orbits. More recent comments from Cameron, however, suggest that this isn't the case anymore. Current reports say that the sequels will all be set on Pandora. Some rumors have indicated that at this new point in time, Jake has become chieftain of the tribe and Neytiri is the high priestess. Their kids could be a big part of the films, too. Expect Quaritch to be plotting ways of getting revenge on Jake.

All that's known about Avatar 2 is that its focus will be largely on Pandora's ocean. (This is why Cliff Curtis' new character is so important, as leader of a "reef clan" undoubtedly based around water.) This is also part of the reason it's taken so long to get the sequel off the ground: Cameron and the visual effects artists at Weta Digital had to create new technology for underwater motion capture. Volcanic environments are also expected to appear.

Cameron has even voiced a desire to get some footage at the bottom of the Mariana Trench — the deepest surface on Earth — using a submersible. This was an early idea, however, and could have changed by now. Then again, you never know; Cameron really loves deep sea diving.

How many Avatar sequels?

Originally the plan was for two sequels. Then it became three that would all be filmed simultaneously, a la The Lord of the Rings. That has since expanded to four sequels, for a total of five films in what is now becoming the Avatar saga. But instead of filming them simultaneously, Cameron will film them back-to-back.

Avatar 2 is (currently) set for a release on December 18, 2020. That date has already been changed something like six or seven times, so it may not stick. If it does, it's possible it could go up against some hefty competition; it falls on the exact same weekend that Disney has used for releasing its last three Star Wars movies. No Star Wars movie for 2020 has been announced yet — it would be a standalone, possibly the rumored Obi-Wan movie — but you can expect Lucasfilm to stake its 2020 claim sooner than later.

Further sequels are aiming for release dates in December of 2021, 2024, and 2025. No reason has been given for the three-year gap between Avatar 3 and 4. Most of Cameron's comments during the writing process suggested that the stories of each sequel will be self-contained, yet contribute to the larger arc of the saga. Some reports have hinted that the films may take an anthology approach, with Jake and Neytiri's story eventually giving way to their children and further descendants.

Avatar 2 Production Has Started

After endless delays, production has finally begun on the Avatar sequels. They're expected to be filmed in James Cameron's favorite format: 3D. Cameron has also mentioned a desire to possibly film at a higher frame rate, like what Peter Jackson did with The Hobbit films. Filming is expected to take place primarily in New Zealand, although Manhattan Beach in California has also been mentioned very recently as where principle photography is taking place. Perhaps SoCal is being used for location shooting?

The first sequel was co-written by Cameron and Josh Friedman, best known as the creator and showrunner on Terminator: The Sarah Connor Chronicles. Many other crew members from the first film are returning, as well. One notable exception is composer James Horner, who worked for Cameron on both Avatar and Titanic. Horner died tragically in a plane crash in 2015.

Having just gotten started filming, and requiring an enormous amount of computer rendering for pretty much the entire movie, don't expect an Avatar 2 teaser trailer until at least 2019. Late 2018 could be a possibility, but don't hold your breath.