Sunny, the human counterpart of Sunset Shimmer, travels with Flash Sentry and Sonata Dusk to Equestria in order to free Adagio Dazzle, Aria Blaze, and Inky Rose from the canopi jars which entomb their souls. They convince the human six to cross over with them, hoping it will lead to a relaxing vacation.

However, a crisis is slowly brewing in Equestria, as portals start to manifest at seemingly random across the land, and ancient beasts start to rampage all over. Could Sunset Shimmer, who sacrificed herself to save the world, somehow be at the center of it all?