All it takes was one decision to throw an entire world into disorder.

When Twilight Sparkle decided to go to Moondancer's party instead of the Summer Sun Celebration and try to catch a late train into Ponyville later, Celestia found herself completely unprepared for Nightmare Moon's return. Unbeknownst to her, one of Twilight's friends, Lyra Heartstrings, did go to Ponyville. There, Lyra tries to fit in, and is thrown headfirst into a world full of new friends, secret agents, prejudice, unrequited love, very requited love, conspiracy, bitterness, regret and the end of all of Equestria.