Twilight returns from a month long trip from Canterlot, and everypony knows something is up. But now that the two strongest ponies of the main six - and indeed, all of Ponyville are incapacitated by a horrible accident, its up to the rest to figure out what's going on. But they soon see that the situation is much more serious than anticipated. Can they get to the bottom of it without the two strongest ponies, especially with everypony on their tail?