Twilight finally perfects the Wing Casting spell, perfecting it down to the most trivial detail. Her friends are more than thrilled to hear and experience the fruits of her labor. All of her friends, except for Rainbow Dash.
Twilight asks for Rainbow Dash and Applejack's help on a journey to get a plant for the princess but Rainbow Dash and Applejack get more from this trip than a simple plant...
It has been almost a century since Twilight and her friends had discovered their destiny, and Celestia has been wracked with constant regret over the fate she has condemned her friends to. Luna looks to those very ponies to help Celestia smile again.