Princess Luna has fallen ill, and with suspicions of foul play floating around Canterlot, it's up to the newly-crowned Princess Twilight Sparkle to find the cause! With the stability of Equestria in the balance, will she find what's making the princess so ill? And if the allegations of foul play are true, who could do such a thing?

(A collaboration between myself and Denim_Blue, who is a wonderful author and you should totally check him out.)