Canterlot High is no ordinary high school, of that there is no doubt. And no one knows this better than the Rainbooms, CHS’ top band, and wielders of magic from the dimension of Equestria. While their fellow students are eternally grateful for their efforts to protect them, one in particular is not satisfied. Flash Sentry, who has secretly gotten tired of worrying about running into magic disturbances all the time, begins to long for the days before Sunset Shimmer showed up and Equestrian magic was introduced into his life (and also when he wasn’t pining for a girl he had no chance with and was already in a relationship). Reuniting with his best friend since kindergarden, moving in with him and his family, and transferring to his school is a big step in that direction, but it isn’t enough for Flash.

Unbeknownst to Flash, Sunset, for reasons she cannot explain, has been feeling homesick for Equestria and wishes to return, and Twilight Sparkle, for reason she cannot explain, has been feeling unhappy in her current relationship and wants to break it off, but is unsure how to do so.

Meanwhile, Flash and his BFF plan to move out of Canterlot city after graduation, and hopefully never see Twilight, Sunset, or the other Rainbooms ever again. However, as they discuss Equestria, and dimensional counterparts, the boys come to a horrifying realization that could mean the end of the world (and perhaps even the multiverse) as they know it. Taking matters into their own hands, they set out to track down the one person who can help prevent it.

And along the way, they meet someone who offers them a VERY interesting deal.