After the defeat of Lord Tirek, Princess Cadence comes over to Ponyville to see the castle for the first time, and enjoy some sister-bonding time with Twilight. On that same day, a unicorn has moved into the small town, who meets Derpy Hooves, the mail-mare, and her friend: Amethyst Star, who homeschools Dinky, Derpy's daughter. A normal day it may seem, but what are the chances that something horrible might occur?