Throughout all of history, one concept has kept both the written and spoken word from becoming an unintelligible mess. That concept is that most holy of grounds known by some as "grammar." It sets down rules for language to follow, and keeps it free of distortion.

Yet something is wrong. The rules are failing. And only one pony so much as suspects that something is wrong. Something that goes deeper than a simple appearance of errors. Something that could be an attack on the very root of language itself.

Princess Celestia tires of constantly being surrounded by decorum, deference, and formality, and decides to take a day off from being Princess. But visiting Ponyville incognito is harder than she expects. Will she be able to fit in and make friends without blowing her cover?

Twilight and her five friends are transported during a botched spell, across dimensions to... Ponyville, Equestria? But not the same one that they knew. Sitting on a bench is Harpsy and Babar. The Doctoress avoids apples from an aspiring Applebuck. And in a library across town, six stallions join their forces as they try to decipher the appearance of filly look-alikes of themselves around Ponyville!