Sweetie Belle's Half-Crystal Daughters must unite with the children of the other Crusaders to defeat the Dark Lord, Eresar once and for all.

Twilight Sparkle receives a letter from Shining Armor telling her to come to the Crystal Empire immediately--and bring her little sister, Twilight Twinkle. But when she gets there she find that the Crystal Heart is missing!

Rarity is sure that Nightmare Moon is returning for the Summer Sun Celebration, but Princess Celestia sends her to Ponyville(ugh) to make friends. What could be worse?