Now that Discord's reformed and friends with a princess and her entourage, he's decided it's time to assimilate himself into pony culture. With Nightmare Night coming up, Discord decides to get into the spirit of things by opening a costume shop in Ponyville. His amazing costumes soon become the talk of the town, and Nightmare Night fever is stronger than ever...

...but is Discord about to play the ultimate Nightmare Night prank on an unsuspecting Ponyville?