When the world is in danger from mystical forces beyond anything anypony has ever seen, only one pony can stop them. Princess Celestia is the Sorceress Supreme.
Sunset Shimmer, the prized student of Princess Celestia, is sent to Ponyville to prepare the Summer Sun Celebration. Unknowingly to her, her actual mission is to stop Nightmare Moon. However, she was never meant to be the Element of Magic.