It's set between trilogies
Rogue One reportedly takes place after Episode III - Revenge of the Sith, where fans saw Darth Vader and the Emperor constructing the first Death Star, and before Episode IV, when the war machine's blueprints are already in Princess Leia's hands.
The movie sports the franchise's most eclectic cast yet
Felicity Jones, who earned an Oscar nomination for her role in 2014's Stephen Hawking biopic The Theory of Everything, stars as Jyn Erso, a rapscallion recruited to steal the Death Star plans. As evidenced in the trailer, she'll lead a team of spies to infiltrate the Empire and steal the Death Star plans. Diego Luna (Elysium), Donnie Yen (Ip Man), Jiang Wen (Devils on the Doorstep), Forest Whitaker (The Last King of Scotland), Mads Mikkelsen (TV's Hannibal), Alan Tudyk (Serenity), and Riz Ahmed (Nightcrawler) costar.