One day, Luna finds a note that was left for her and Celestia by their mother, Queen Galaxia. The note mentions a hidden room, underground somewhere in Equestria, that is full of ancient valuable artifacts that were traded, crafted and stolen during times of war when Galaxia was a filly. These valuables are possibly worth more than anyone could ever imagine. The two sisters decide to task Flurry Heart, Neighsay, and the Young Six with finding this legendary treasure and bringing it above ground.