Twilight Sparkle, newly appointed Princess of Magic, has been having recurring nightmares for several nights since she became a princess, with each nightmare bringing the same horrific visions as the last. In her quest to find answers to the cause of these nightmares, she only uncovers more questions, ones she fears she may not be able to answer on her own. With the help of the Princess Luna, Twilight and a group of her closest friends and family embark on a dangerous personal mission to uncover the truth about these nightmares and how they (according to High Princess Celestia) are somehow linked to sudden sightings of an island off the Equestrian Coastline, the same island that Celestia forbade Twilight from venturing to. What they find there, however, will not be answers to their questions, but horrors beyond their darkest fears...