Rarity discovers that she is a very rare kind of pony; a Marshmallow pony, which are born only once every millenium. But some strange ponies appear attempting to capture her, and so Rarity must escape with all who know her secret.
Spike and Rarity seem happy enough together, but Twilight knows their dark secret. How much longer can she keep it quiet? More importantly, how much longer can she hold herself together?