Spending Hearth's Warming with her marefriend is wonderful, yet Sunset can't help but feel reminded that she's not truly of this world anymore. Strangely, Twilight can relate.
Sunset Shimmer, practitioner of friendship, twice savior of Canterlot High, alicorn. She's offered to help Twilight's new student as the whole group travels to the Crystal Empire for a Crystalling. Should be a relaxing, stress free trip. Right?
Future universe. "Sister" Princesses Sunset Shimmer and Twilight Sparkle mourned the loss of Equestria's favorite Princesses - The royal natural-born alicorn sisters Celestia and Luna. In an attempt to win them back, they resurrect them - as fillies.
Pinkie Pie plays match maker for all her friends, including her family. Afterwards, Pinkie Pie realizes that Sunset Shimmer doesn't have one. Pinkie puts her on a dating website... Hilarity insures.
After half of Twilight's mane gets ripped off, she decides that it's time to visit the Author of All Beings in order to give herself a sparkly magical mane, just like Celestia. One problem: the Author of All Beings is a massive jerkface.
Realizing their feelings for each other was only just the beginning. Now, the newly crowned princess Sunset Shimmer, and Lockon Astros will have to travel together down a new path that neither one has taken before on their own; The path of love.
Thirty moons after Twilight helps her see the light, Sunset Shimmer has finally decided to return to Equestria to face her punishment and make amends. Along the way, she makes more friends, and there are a few other surprises in store for her.
Sunset Shimmer finally returns home to Equestria to right her old wrongs, unfortunately the sins of the Human World follow her back and put everypony in Equestria in danger.