Twenty years after Twilight Sparkle becomes the princess of friendship, the princesses are disturbed by prophetic visions of the decedent of an old ally, shades of an old enemy and betrayal. Not long after they're disturbed by their visions they are alerted to a strange two-legged creature speaking in a strange tongue coming across the tundra from the far north, skirting the edge of the Crystal Empire. The only clue to where it is going is an old map in its possession leading to the old Everfree Castle.