When an childhood friend of Twilight's is killed, she and her friends find themselves in a race against time to find the murderer and the secrets they hold. With each step leading further into a forgotten history, Twilight must uncover a secret long buried and prevent an ancient prophecy from coming to pass and erasing a thousand years of harmony.

A rare lunar phenomenon revives an ancient evil long forgotten, and the Elements of Harmony find themselves stalked by an evil more powerful than any they have faced. As painful secrets of her past come to light, Celestia is forced to face her own demons if Equestria is to survive.

When the ponies of Equestria decide to explore beyond the bounds of their peaceful land, they find a world much different than their home, filled with wonders and dangers greater than anything ever known. Ponykind must forge their own destiny in a world where survival depends on much more than the power of friendship.