Rogue One follows the Rebel alliance making a risky move by stealing the plans for the Galactic Empire’s new weapon. This is one of the used Death Star data disks the film is centered upon and contains the plans for the Empire’s ultimate super weapon, the Death Star and its weakness. In the Star Wars timeline this is also be disk inserted into R2-D2 by Princess Leia the projects her requesting help from Obi Wan Kenobi.