A mare named Dust Runner gallops through cities, villages, deserts, dried-up plains, everything, just so she can gather the materials to survive. Food. Water. Shelter, for a little while. All while trying to fight the other survivors of The Strike. The Strike was what the survivors, and anypony else, called the sickness that destroyed the land. There were The Stricken, who were ponies that had gone insane with the disease that hadn't died yet, and The Shielded, who were ponies that were immune to the disease. Dust Runner was a Shielded.

(WARNING: Inspired by The Maze Runner books.)
(WARNING2: I put the gore tag there for a reason. GORE WARNING.)