Twilight Sparkle was merely trying to go out to lunch with her number one assistant after a long morning in the lab when a strange dome of energy passed over them. Now on the other side, with Spike missing, no one in Ponyville recognizing her and certain facts about the town and Equestria she had taken for granted changed, Twilight has some questions.
What happened?
Where is she?
How can she get back?
And perhaps most importantly:
Who is this "Champion of Princess Celestia, Sunset Shimmer Defender of the Realm" everpony keeps going on about?

This story is set in season 3, before Magical Mystery Cure. All other episodes have occurred, or are not relevant.
Characters who deserve to be on the main character list have been removed to prevent spoilers.
Edit: Updated to teen upon reflection of the fact that it is going to get rather violent latter on.
Cover art by the fantastic Lord-Giampietro of deviant art. http://lord-giampietro.deviantart.com/