Set directly prior to the events of Star Wars: A New Hope, Rogue One features Felicity Jones as a member of the ragtag rebel team assembled to steal the Death Star blueprints that Princess Leia will eventually dispatch R2D2 to deliver to Obi-Wan Kenobi on Tattooine. Jones' character, Jyn Erso, is the daughter of engineer Gale Erso (Mads Mikkelsen), who in the film is held captive by the Empire and forced to provide key work in the Death Star's completion. Darth Vader will also appear in Rogue One.
The clip, which is introduced by Disney CEO Bob Iger, is mainly comprised of scenes and shots already glimpsed in previous Rogue One trailers, though some shots are extended - and the preview places sequences like the beachfront battle with AT-AT walkers in a slightly different tonal context. Overall, the clip emphasizes the push to establish Rogue One as being different in feel and aesthetic from previous installments in the franchise; while still making use of familiar Star Wars iconography.
Though reports of re-shoots dominated news around the film during the summer, Disney/Lucasfilm appear to be fairly bullish about Rogue One's box office prospects. The film is being touted as a test case for the viability of already in-motion plans to space out the release of mainline Star Wars film installments with spin-offs and side-stories in the intervening years. Two such projects include a now in pre-production feature following the exploits of a young Han Solo and possibly a movie that revolves around bounty hunters such as Boba Fett down the line.
Rogue One's December 16th release will also serve as a major promotional push for the rest of Disney's slate; including, multiple upcoming animated films, live-action retellings of the studio's animated classics and the latest installments in the Marvel Cinematic Universe. The first trailer for Spider-Man: Homecoming (a joint production of Disney, Marvel Studios and Sony Pictures) will be attached to prints of Rogue One, in particular.
Source: The Entertainment Channel