Somepony's plotting something... very mysterious indeed.
Twilight's been called in to make sure everything's alright, but not everything is as it seems. A large undertaking is underway. Many ponies will have some hand (hoof?) in shaping the coming events, and Equestria will never be the same, after.

(I found the cover on Google Images. I take no credit for it. Also, I the TF2 theme has absolutely no relationship to this story.)