When an insidious evil threatens the Crystal Empire, the Princesses must call upon the most unlikely pony; Sombra. Can he overcome his own darkness in order to save the empire from a far worse one?
Rarity orders a collection of gems from the crystal empire to give her new designs that little bit extra. Included in the shipment is a stone that is far more than what it seems. The gem holds a dark secret and the key to one pony's life.