Now that all of the girls have reunited after the events of the Fall Formal, it's time to party! And what better occasion than a costume party for Halloween? Pinkie Pie is hosting the shindig and Rarity offers to make costumes for each of her friends. What costume will each of the girls choose and will Rarity be able to pull off making all of them in time? What about their newest friend, Sunset Shimmer? Will the party be a nightmare night or a chance for old and new friends to share a laugh?