The war between pegasi and earth ponies has raged for eight long years. Five years ago, the pegasi invented a powerful tactic which changed the course of warfare forever--they learned how to manipulate the weather. With the power of nature against them, the earth ponies seemed doomed to fail. That is, until a pegasus meteorology agent is captured on a routine mission. Rather than kill her, one earth pony captain comes up with a novel idea all his own--convert her into a double agent. Perhaps the war can yet be won.

This takes place several years before the foundation of Equestria.