"Star Wars: Rogue One" doesn't start production until the summer, but fans now have a clearer picture of what the movie -- the first of multiple planned "Anthology" films that are set in the Star Wars universe but not part of the trilogies -- is actually about.

Revealed Sunday at Star Wars Celebration in Anaheim, here's the official logline: "A rogue band of resistance fighters unite for a daring mission to steal the Death Star plans and bring new hope to the galaxy." During the panel, "Rogue One" director Gareth Edwards confirmed the movie takes place between Episodes III and IV. "My favorite movie of all time is 'A New Hope,'" Edwards said. "So a little bit more towards IV."

The panel, which also included Lucasfilm President Kathleen Kennedy, Lucasfilm Vice President of Development Kiri Hart and Industrial Light & Magic Chief Creative Officer John Knoll ("Rogue One" is based on an idea from Knoll) additionally contained the reveal of the very first "Rogue One" teaser -- brief and rendered by ILM, as the film hasn't started shooting.

The teaser hasn't made its way online yet, but opens with the voice of Alec Guinness, specifically these words from Obi-Wan Kenobi in "A New Hope": "For over a thousand generations, the Jedi Knights were the guardians of peace and justice in the Old Republic. Before the dark times. Before the Empire." After panning through a peaceful area flush with vegetation, a TIE Fighter flies by, leading to a reveal of a portion of the Death Star, which looks massive in perspective. That leads to the "Rogue One" logo (with "Anthology" underneath the title), with what sounds like the voices of frantic X-Wing pilots -- which starts to cut out, as the logo scrambles.

During the panel, "Rogue One" was described as a war film at multiple points -- it's called "Star Wars" after all, as Edwards pointed out -- with Neil Corbould, whose credits inlclude "Black Hawk Down" and "Saving Private Ryan," working on the film's special effects. "The one [word] we say the most is 'real,'" Edwards said, describing the tone of the film. "The realism. The fact that it has to feel like that is a real place that we're really in. It's going to hopefully feel very natural and subjective."

Fitting in with that realism, Edwards said, "The absence of the Jedi is omnipresent in the film. It hangs over the whole movie. It comes down to a group of individuals that don't have magical powers, that have to somehow bring hope to the galaxy."

Edwards acknowledged that the original Star Wars films -- which he was such a fan of he spent his 30th birthday visiting "A New Hope" shooting locations in Tunisia -- was very morally black-and-white. "Our movie is basically the grey that leads to that polarizing event," he said. "It's the reality of war. Good guys are bad, bad guys are good. It's complicated, layered, a very rich scenario in which to set a movie."

Thus far, Felicity Jones remains the only confirmed casting for "Rogue One," and Edwards revealed that her character will be a Rebel soldier. "She's the complete package," he said. "We were just very lucky that she was a Star Wars fan, and dropped everything to come on board."

Additionally, the panel confirmed that "Rogue One" and its subsequent follow-ups will be called Anthology films. Previously, they've been colloquially referred to by fans and press as spinoff or standalone movies. The only other confirmed Anthology film at this point will be directed by "Fantastic Four's" Josh Trank, who was scheduled for the panel but unable to appear, with no new details on his project revealed during the session.

"We really wanted freedom to do some films that would be able to stand on their own, tell unique stories that can vary in scale and vary in genre," Hart said.

Hart also noted that "Rogue One" takes place in the same approximate place in the Star Wars timeline as current animated series "Star Wars: Rebels," and said that kind of overlap could create opportunities. "When there are things that feel they are falling in adjacent places in the timeline, we can look for ways for them to talk to each other," Hart said. "But we never mandate that. We let the stories evolve the way they want to."

"Star Wars: Rogue One" is scheduled for release on Dec. 16, 2016.