Rarity, Applejack, Sweetie Belle, and Apple Bloom were on the train towards their holiday destination. But said trip had to be cancelled. Now they're on a remote island while Equestria is threatened unknown beings.
Everyone Rainbow Dash knows is dead. She lives as a legend in a world that forgets her, and as of now, she tires of it. She hopes to forget her troubles by letting the sky guide her like it did so many times before.