On a night when the moon itself hides behind the black curtain of cloud, a little white pony dreams of a fantastical place. A cave of sorts, all aglitter with gemstones of every size and color imaginable. But there's something eerie about it, a shiver creeping its way up her back. Miss Rarity awakens in her room eager to find this mysterious dream world. With her trusty cat, Opalescence by her side, she will embark on an incredible adventure across the Equestrian countryside. Except it isn't all merely whimsy and fun, a whole host of creatures, familiar and not so familiar, make their appearance. Will Rarity get to find her mysterious cave? Or will she vanish, forever beneath the earth?