A mutated breed of fungi throws Equestria into a world-wide pandemic. No-pony knows where it came from, only that a stallion; known as Patient Zero, had found it in the Everfree Forest.

Equestria has been quarantined, cities have become heavily guarded and quarantined hubs for civilization. Outside of the walls, lie independent settlements and nomadic groups, fighting for their own survival. The infected are spread throughout the Equestria, even inside a few quarantine zones.

This is the story of one mare, living inside the Manehattan quarantine zone. Through an unforeseen circumstance, she manages to be put into a situation that leads her outside the walls; where she must learn to survive and live to see another day, or end up as another statistic