Its the year 2250, sixty years since the start of the Daemonic Incursion, and humanity has all but left Earth, their sole presence being the super fortress Bastion, a country sized fortress situated in what once was Somalia. In an attempt to end the incursion, human military forces entered the breach twenty years ago to take it out at its source, by releasing the titans. In the Equestria, Princess Celestia that her sun is nearing its final days and is about to resign herself to her fate, an astronomer who just happened to be passing through, comes up with a plan that will lead to the survival of the pony race, by leading them through Tartarus and into a rift to another world.