Ever since their firsthand experience with the paranormal, Twilight Sparkle, Rainbow Dash, and Applejack founded the Ponyville Paranormal Society (P.P.S.). With their investigations making a huge hit, none other than Princess Celestia herself asks the P.P.S. to investigate the main castle building. Thinking it was going to be their average ghost hunt, they soon find out that it is something much more sinister and darker than they've ever encountered. Can they reveal the dark secrets held within the castle walls? Can they wield the power to drive this evil entity away or will follow and haunt them for the rest of their lives?