Shadow Chaser's second tale follows him and Rainbow Dash on a voyage to the lost city of Marelantis, an ancient underwater city, thought lost for ages. But before they can even begin Applejack notices the Cutie Mark Crusaders have gone missing. As Shadow, Rainbow, and the insisting Applejack, chase after them, they quickly find themselves caught in a deadly chase to Marelantis and must use theirs wits, speed and strength to overcome all odds and rescue the Cutie Mark Crusaders.