The nation of Equestria is under siege. After Cozy Glow's victory, ancient enemies and new threats have arisen to threaten the ancient realm with utter annihilation. Without alicorn magic, Equestria must rely on the strength of the common pony to withstand armageddon.

Gemstripe Boulder is one such pony. Once eager to do his duty and serve the princesses, Gemstripe finds himself beset by doubts and fear as the time of his deployment draws closer. The cannon's scream echoes loudly from the distant front, and the burning shadow of war hovers menacingly over everypony.

Now he must march into that gaping maw, for the princesses, for Equestria, and all he holds dear, lest the fires of doomsday run ever wilder and consume it all.