Sunburst has been dutifully fulfilling his responsibilities as a Crystaler to the newborn Princess Flurry Heart. Although, given her young age, his 'lessons' mostly amount to extended baby sitting sessions. Though uncertain, Sunburst is proud of his position, and takes his role as the newborn Princess's guardian seriously. That is why, when a shadow suddenly falls over the heart of the Crystal Empire, he makes getting her to safety his first priority. As jagged dark crystals erupt and spread outwards from the Crystal Castle, a strange madness seems to spread through the populace.

Can Sunburst keep his goddaughter safe when the entire population of the Crystal Empire turns against him? What is the source of this strange madness that has gripped the populace? Will Twilight and her friends be able to aid him? And just who is the 'Empress'?