It has been three months since Lightning Dawn and Krysta quite literally fell into Twilight's life, leaving quite an impression on her before departing as swiftly as they had come. In that time, in amongst the hectic life she leads in Ponyville, Twilight has been searching for a way to contact her two lost friends. Finally, she thinks she has found it: the Heart of the World, a legendary being of unknown kind but which, if the tales be true - and when are they now where Twilight and her friends are concerned - had the ability the communicate with other beings across space. If Twilight can find the heart, she might be able to contact Lightning and Krysta, perhaps even help them return to Equestria.

So, with her faithful friends by her side, Twilight sets off on a journey deep into the heart of zebra country, searching for a way into to the bowels of the earth where the Heart of the World is said to dwell. The journey will not be easy: zebra warriors, hidden defences and the malice of the mysterious Raven will dog the steps of Twilight and her companions. But at the end of the journey, at the Heart of the World, Twilight might just find a way to mend her own aching heart.