As a favor to Applejack, Twilight Sparkle has agreed to do her best to help Apple Bloom overcome her recent rash of terrible nightmares before her lack of sleep ruins the Apple Harvest Festival for her and her friends. Luckily, a lifetime of obscure study has come through again, and Twilight knows of a way to figure out what's going on in the little filly's imagination that's causing her to be tormented with these dreams- an ancient, mysterious spell called the DreamWalker spell, that enables the enchanter to enter the dream of a sleeping pony. But not everything is as it seems, and all of Twilight's friends- all of Equestria- might be in danger. Can Twilight and Spike escape the maze of nightmares and return to the real world in time to save it?