Luster Dawn is the Princess of Unity. Irradiance the Guardian of Harmony. Two foes down, none to go. Or Irradiance wishes. As things settle back into place, a strange guard shows up in Canterlot castle, and suddenly Irradiance is seeing the face all across town. The Crystal Empire is encased in shadows and snow once more, and Irradiance and the Elements of Polyphony are sent to investigate. When a hidden secret comes to light about Irradiance's past, it turns out that he's the only one that can defeat this upcoming threat. At least, if he can shake these strange voices in the back of his head.