A few years following the events of "Chapter 8", Twilight is blindsided by the revelation that Princess Celestia and Princess Luna are preparing to retire and allow Twilight to become the new ruler of Equestria, leaving her conflicted over whether or not to accept the offer. At the same time, an evil ram named Grogar recruits the worst of the worst of Twilight and her friends' rogues gallery in a plot to take over the kingdom, and the ponies must defeat them once and for all.