Deep down his forgotten complex of enchanted rooms and trapped corridors lies buried the one wicked book whose existence threatens all Equestria. The one book he has left for his heir to wreak havoc and ravage the kingdom with.
Celestia cannot permit such a volume to endure.
So Twilight accepted to face the dangers of the underground compound to recover that accursed volume and bring it back to her mentor for destruction.
An expanded version of the (terrible) minific submitted to the October '15’s WriteOff event, 'Illusion of Choice'. Inspired by the graphic novel 'On the contrived Earths', part of the 'Valérian and Laureline' SF series.
Set in season 1/2/3 (featuring a plain, vanilla Twilight).