Twilight discovers that one of the books in her library is housing dark magic, and, with the aid of her friends, attempts to destroy it with the Elements of Harmony. But when the book sucks them all into it's depths and brings them back to an earlier stage in their life, the fillies must fight against a world they once knew to recover the Elements and get back home.

Based off of the N64 game, Yoshi's Story. The game was given some mixed reviews, but the premise made for an interesting crossover concept. That being said, in the spirit of the game, this will sort of be a choose your own adventure. Four paths, four chapters per world. Each one has a unique story, but all will be valid choices in the long run.