Ally Corne goes on a trip to an island to an old barn her grandmother, Grammy Tia, had owned. It was said to have 'strange' ponies living there, but now it was abandoned. But then she discovers that the ponies are still alive. And waiting.
Pinkie asks Twilight to make a portal to another world, and that leads her to a world of freakish ponies who are incredibly shallow and girly, otherwise known as G3 MLP.
Rarity was just trying to do Rainbow's mane. Promise. But when those hairless THINGS showed up, she ran, leaving Rainbow tied to the chair with the creatures surrounding her. Now Twilight must go through the mirror once again to save her friend.