An "automaton" resembling a pony made of living glass is accidentally freed from its prison deep in the Castle of the Two Sisters. Though it acts supremely unhelpful, Twilight manages to learn of an ancient evil growing steadily across the land, infecting the very nature of the world. In the face of doom, the Elements of Harmony must try once more to save Equestria.

It would be a lot easier if the glass pony would just give them a straight answer...