Equestria has become a post-apocalyptic wasteland terrorized by roving bands of irradiated mutants. The princesses were vaporized years ago, the sanity scourge has turned unicorns into mad raiders, and the dead don't remain peaceful for long. Even the environment fights against ponykind as rivers dry up and ashen clouds block the sun. If anypony is to survive, they stand a better chance with friends, ponies who you can trust to keep you alive when your back is turned.
Which makes it all the more horrifying when Summer Breeze discovers her comrade-in-arms has been replaced by a changeling. Desperate not to lose the one pony she trusts absolutely, she must confront his replacement in order to pinpoint his location before time runs out, but how can she trust the word of a deceiver?