Twilight Sparkle has lived all her life as a scribe in the walled city of Canterlot, protected from a world she's only read about. She doesn't yearn for travel or adventure. Life as a scribe and Royal Librarian is just fine.
But the Solar Empress Celestia has missions that need doing and only one mare she trusts with the responsibility of preparing for a coming disaster. Thus began the legend of 24 Hooves.