My Little Pony: Equestria Girls: Through the Mirror
by G.M. Berrow
When her crown is stolen from the Crystal Empire, Princess Twilight Sparkle pursues the thief, Sunset Shimmer, into an alternate world, where she finds herself turned from a pony into . . . a girl!
In order to regain her crown and return to her home in Equestria, Twilight Sparkle must learn about this strange new world and defeat Sunset Shimmer in a competition to be crowned princess of the Fall Formal at Canterlot High. Luckily, the magic of friendship never changes, and Twilight has the assistance of five girls who remind her of a certain group of ponies back in Equestria . . .