Lately, Princess Cadance has been feeling inadequate. She's spoken of this briefly to Twilight Sparkle but her longing for a grand adventure is really starting to get to her as are the thoughts that she isn't doing all that she can.
Long ago, in the dead of night, Luster Dawn saw a dark figure in Canterlot Castle's throne room. Longer still before that, Princess Twilight Sparkle and her friends defeated one of Equestria's greatest enemies in that same room.
Princess Luna disappears from Equestria with hopes of saving the world and is accompanied by the enigmatic Sombra. Meanwhile, Celestia tries to bury secrets as immortal as she is and Cadance must choose her loyalties carefully...
Sombra is by no means an easy opponent. He is a manipulative wild card who has cheated death twice, and seeks to do so one more time. But, how many ponies can cheat death forever?