Years before Sunset Shimmer crossed the portal and became one of the secret identities of The Mysterious Maiden Do Well, a criminal was arrested in Canterlot Town; the newspapers gave her the name "Nightmare Moon", but the name of the woman under the mask was Luna - an identity revealed after she was caught and arrested.
Few years passed since she finished serving her sentence and she was arrested again for the same crime, but the evidence isn't pointing at her as the true culprit, and there seems to be more about this new criminal than meets the eye. Will you do what has to be done, Maiden Do Well?