It all starts simply enough with Chrysalis sending two of her most trusted changelings to infiltrate the bearers of the Elements of Harmony, but now she has a civil war on her hooves that threatens to spill over into all of Equestria.

Celestia and Luna have read the signs and enlist the Mane Six to handle the changeling threat forever... by stopping it before it ever happens. Using one of Starswirl the Bearded's most coveted spells, they have a chance to go back to prevent Queen Chrysalis' tragic origins, but one misstep could destroy the present that they came back to protect, and when they get tangled up in the history of the Elements of Harmony, things get even more complicated.

(Conceptualized prior to season 3 or the comics, though it takes place shortly after the events of The Crystal Empire).