The Ursa Minor has suddenly returned as The Mane Six have left for The Dragon Lands on official "friendship business". Now that he has matured into a Ursa Major, not only is he much stronger than ever before, his temper and recklessness are also deemed a threat as he suddenly attacks Ponyville, alongside 5 other beasts of equal size and power, with the sole purpose of revenge. But revenge for what?

Without the Elements of Harmony, it is up to Starlight, Trixie, Princess Celestia, Princess Luna, surprisingly Discord, and all of Ponyville, to prevent the destruction of everything they hold dear. But that can only happen if they find out why the Ursa Major is driven by vengeance.