In a past Canterlot, Adagio Dazzle is cued to become one of the newest maid mares to one of the richest business mares of the time, Berry Harvest. But all is not as it seems in the beloved capital.
Illegal business' thrive, and rivalries fester under the polite smiles, and racism and sexism flourishes for all its worth, and crises are around every corner, and Canterlot begins to rot from the inside out, while the Princess is nowhere to be seen.

My own interpretation of how the three sirens from Rainbow Rocks met, gained their powers, and got banished :)