In the far future, Equestria is in ruins. Changelings are roaming, an infection is raging thanks to a "vaccine" from the past, and survivors of the epidemic hide underground attempting to survive from the world above. The vaccine has two ways of counteracting with different ponies, it either revolutionizes them into ponies that are immune to any disease, or they become flesh eating Generation 2 Changelings from the vaccine's failure to certain ponies. Light Rain, a young "serumized" pony, decides to lead a small resistance against those who have begun this terror. When they all have one last chance at changing the future thanks to the infamous Doctor Whooves. After losing his friends and now stranded alone in present day Ponyville, he is now more then ever ready to stop the impending apocalypse. Will he complete his mission, and change the future?

Or will a certain pony from the past become involved with his mission...