Director Gareth Edwards used the Star Wars celebration on Sunday to premiere a concept reel to preview the mysterious new movie Rogue One. The film is one of a series of new films exploring other stories outside the core saga.

Felicity JonesFelicity Jones is the only confirmed cast member for Rogue One

"For more than 1,000 generations, the Jedi Knights were the guardians of peace and justice in the Old Republic. Before the dark times. Before the Empire," a voiceover read in the concept reel.

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Set between the third and fourth movies in the saga, the film will focus on a group of resistance fighters who unite to steal the Death Star. The Oscar-nominated actress Felicity Jones, most recently seen in The Theory of Everything, is the only confirmed cast member. The film shoots in London this summer and is set for release on December 16, 2016.

"We wanted to see fear, warmth, all of those aspects that everybody has," Edwards said of the film, noting that the "absence of Jedi is omnipresent."

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Edwards added that the characters in the film realize that "gods are not coming to save us," adding, "It comes down to a group of people who don't have magical powers who band together to bring hope to the galaxy."

Chris Weitz, who wrote the recent Cinderella screenplay for Disney, has penned the script for Rogue One based on an idea from visual effects supervisor John Knoll.

Kiri Hart, vice president of development for Lucasfilm, said that the new anthology films will vary in "scale and genre," adding, "We wanted freedom to do some films that would be able to stand on their own and tell unique stories."

"They can still feel like 'Star Wars' and be 'Star Wars'"