Something very odd is happening to Sweetie Belle. First, her magic is powerful and uncontrollable all of a sudden. Second, old scars that disappeared years ago have come back. Third, her mane and tail are waving like the princesses' do. Confused, everypony goes to investigate. They may find that there's a lot more to this filly than they thought.
Any criticism is both welcome and appreciated :)
The artist who made the vector used in the coverart is http://pvt-llama.deviantart.com/ .