That question plagues Lieutenant Nathan Ward as he and his fellow mounted police officers defend one of the last cities on Earth. Columbia, Missouri was spared a direct hit when the bombs fell, but it’s become a target: refugees flood the city, gangs run rampant, an enemy army closes in, and the Corporations responsible for the catastrophe conspire in the shadows. For the mounted officers, morale couldn’t be lower. Most lost their loved ones and hometowns when the bombs fell, and the citizens of Columbia have grown resentful of their presence in the weeks since. Food riots and protests are the order of the day, and it’s more than some can handle. Fortunately, they don’t fight alone, as some Corporate members value peace over power, chief among them Specialist Aster and her elite team of soldiers. Together they stand ready to face off against this approaching army. But the city harbors a secret beneath its rubble-strewn streets, a secret that a Corporate director will pay any price to attain. Even if it means raining fire from the sky. Faced by threats on all sides, will the Thin Blue Line hold?