Thought to have been killed as a filly, Twilight Sparkle is discovered to be returning to Canterlot. Instead of a joyous reunion awaiting her, a trail of destruction follows her as Celestia and Luna struggle to discover how, and why, she's returned.
A thousand years ago, the three pony tribes failed to form a unified nation, and war doomed the unicorns to near-extinction. Twilight and Applejack now seek the Elements in the hopes of ending the long conflict between pegasi and earth ponies.