When the Empire catches up with Galen, Jyn hides while Commander Krennic (Ben Mendelsohn) kills her mother and drags her father away. Made orphan she is rescued by uncompromising Rebel Saw Gerrera (Forest Whitaker) and raised as part of his cadre.
Now, fifteen years later, going by an assumed name she is stuck in an Imperial labour camp having long forsaken any ideas of resistance to the Empire when Cassian Andor (Diego Luna) "rescues" her.
Cassian is a Rebel spy who needs to speak to Saw about an Imperial defector and he thinks Jyn is his way in. The increasingly violent and paranoid Saw and the Rebel Alliance parted ways years ago. This defector claims to have information about the aforementioned superweapon.