While on a much needed vacation from planning and attending this years Grand Galloping Gala, the Mane 6; PinkiePie, Twilight, AJ, Rainbow Dash, Fluttershy and Rarity are send on an expedition to an area that until recently has been magically hidden from the world by Princess Celestia, their mission; to investigate the reason for the barriers failure, little knowledge of what lies in the city is found. And even the Royal Library only refers to the area as "The Dead City" Where the remnants of a world long destroyed and the ghosts of the dead, long for peace. And a seemingly harmless investigation turns into a brutal fight for survival, and only the most determined will make it out alive.
(My take on what happened after the Events of To be Remembered http://www.fimfiction.net/story/66122/to-be-remembered)