On a particularly normal morning, Twilight Sparkle learns that Starlight Glimmer has been up to time-altering shenanigans again. She claims that she had to stop Rainbow Dash from performing another Sonic Rainboom in order to save Ponyville from catastrophe, but Twilight had seen enough to know how important Sonic Rainbooms are and how Starlight should absolutely never try to stop one ever again. The future of Equestria could depend on it, after all.

However, Twilight's attempts to fix Starlight's meddling only seem to make things worse. So do her attempts to fix her own previous attempts. As well as her attempts to fix those attempts...

Perhaps Starlight had been onto something.

Rainbow Dash always considered herself to be the coolest of the cool, the fastest pegasus in Equestria, and the bravest pony around. She had achieved her dream of becoming a Wonderbolt, had her own fan club, and even saved the world with her friends at least a dozen times now. But when a magical accident results in her waking up as a young filly one morning, Rainbow Dash suddenly finds her awesomeness to be a little strained.

With Twilight unable to break the spell for a while, the once proud mare must learn to get used to her new size and hopefully make the most of it. Unfortunately, her old fillyhood habits, insecurities, and immaturity that she had long since outgrown have made a comeback as well, making Rainbow's life that much more complicated. To make it even worse, those around her are finding it more and more difficult to take her seriously as an adult...

...And Rainbow Danger Dash does NOT need a babysitter!