Scar is defeated and the Pride Lands and Equestria is at peace once more but nothing is the same anymore as far as Kion and Twilight are concerned.

After seeing his friend struggle with being accepted back into her leadership role of the Pony Guard, Kion decides that a vacation is in order for Twilight for her to recuperate. Although said vacation turns into an world-stake mission when they receive a message from an equally struggling Sunset Shimmer in Canterlot High, informing them that three new students have suddenly arrived with a thirst and hunger for power at the school along with the world with new friends from the Pride Lands past helping them out.

The Prince and Princess along with both Spike and Bunga all travel through the magic mirror where they once again meets their bonded friends human counterparts of her bonded ponies along with a reformed but mentally scarred Sunset Shimmer, who is still struggling with letting go of her past. The Lion and Pony Guard band together to form, The Rainbooms in order to compete in the school's Battle of the Bands in order to defeat The Dazzlings and their Pride Lander allies, before they turn the whole school against each other.

Can Twilight regain her confidence in order to make the counter spell they will need to defeat their foes? Will Sunset Shimmer let go of her past in order to move on and help her friends?