With Sweet Apple Acres struggling during a recession and a drought, a sixteen year old Apple Bloom joins the military to bring in some extra income and keep her family out of the poor house. Scootaloo and Sweetie Belle enlist with her, convinced that nothing can break up the Cutie Mark Crusaders. With Equestria enjoying an unprecedented period of peace and harmony, what could go wrong?

Scootaloo is pressured into the Airborne, separated from her friends. To get to their deployment, Sweetie Belle and Apple Bloom need to take a ride on a marine boat, dodging the verbal stabs from a marine chief and the clumsy flirtations of a lance corporal. As they proceed downriver, the ponies on board PBR-471 grow closer. The heat of battle acts as the catalyst for the bond between Apple Bloom, Sweetie Belle and their marine comrades.

It becomes evident that something very big is about to go down in Equestria. While the unfortunate sons and daughters in the Expeditionary and Marine forces gear up for battle, Celestia calls a war council. What seems like a small uprising proves to be something that could jeopardise a devious plan over one thousand years in the making.