Sara's parents were born in Altea. So was her sister. So was she. She has grown up within the confines of the "perfect world," and she never doubted that it was all that it claimed to be. She has never in her memory been assaulted. She has never in her memory been afraid. She has never in her memory been worried about her well being or her future.
But after a single life-changing incident, Sara learns that her memory may have been lying to her all along.
She didn't mean to overhear them talking about the terrorist Xi. She was doing her job, her internship, doing inventory in a lonely supply room. And then they were there, standing outside the room, talking. And none of it would have amounted to anything if that camera hadn't been there the entire time, recording Sara's presence.
And later, Sara thinks, after the memory of her entire existence has been erased from everyone she knows and loves, the camera should have been her first clue. But, she knows, it no longer matters how she ended up here, doing what she's doing. Because she wouldn't have it any other way.
She's a Bombardier, and if takes dismantling Altea piece by piece in order to get the world to see the atrocities its government has committed, then so be it. Because according to the world, Sara Miller no longer exists. And if Sara is nonexistent, then as far as she's concerned, she can do whatever the hell she wants.
And the only thing she wants is for Altea to fall.