Twilight Sparkle - magus, heroine and Princess - has learned of worlds overlapping Ungulatia in space and time. Though this has been a well known phenomenon, safely traveling to these other worlds has always eluded pony mages. But now - after years of research and careful experiments - she prepares herself for the most audacious of all experiments: stepping hoof on the surface of an alien world and returning safely! What wonders will she find once she walks through her magic portal?

This assumes that Equestria Girls never happened.