An unexpected friendship begins to bloom between two young princesses. Differences in the way you live, your race, and what you eat doesn't matter. It’s what’s in your heart that matters... Right?
Where was Luna during the attack on Canterlot? Why did she not aid her sister in protecting the city? Perhaps she was protecting other ponies... or perhaps something more sinister occurred.
Luna has been redeemed by the elements of harmony, but is finding that salvation is harder to come by. Perhaps the Moon, her prison for so very long, is truly where Luna belongs after all.