Five years have passed since the retirement of Princesses Celestia and Luna, and Princess Twilight Sparkle now reigns over Equestria with the help of the Council of Friendship and her loyal Royal Adviser. Equestria has known nothing but peace and prosperity ever since the defeat of Chrysalis, Tirek, and Cozy Glow, which felt like an eternity ago.

Far away in a distant land known to no Equestrian lives a secluded and foreign city. Once alive and full of riches, Ponypeii is now a shell of its former self, with destruction, decay, and death at every turn. Now, King Colossus has no choice but to turn to the Equestrians for help. If the four vicious Sisters are left unchecked for much longer, their way of life will be destroyed. And Equestria will be next....