After the Siren's defeat, Aria has been bored with her existence while Adagio and Sonata have been able to move on with their lives. On one of her daily routines, Aria happens to run into a former enemy, who also seems to have forgotten who Aria was.
Shortly after the Dazzlings witnessed the Rainbooms' argument with Sunset Shimmer, they concocted a plan that would surely put Canterlot High at huge risk and inched them closer to achieving their goal: making Sunset one of them.
When Sonata and Aria return to school after disappearing for several weeks, Sunset begins to find out the reason the girls turned into such evil beings.