Modern Equestrian history holds that the country of Equestria was founded when the Royal Pony Sisters, Princesses Celestia and Luna overthrew the Lord of Chaos, Discord, with the Elements of Harmony. Of the time before, little else is known, except for what the Princesses themselves reveal.

When on the sixth night after the defeat of Nightmare Moon, and the passage of the Elements of Harmony from their old bearers to six new ones, a powerful pony prisoner from the Princesses' past plots to prevent them from prolonging his punishment. Celestia, Luna, and the Elements of Harmony now face a moral dilemma. Is it just to imprison him again for crimes that he denies committing, or is this pony too great a threat to turn loose on the ponies of Equestria? (Now with alliteration!)