In the year 2141, the Coalition of Aligned Solar Territories was strained between the victors of World War III some eighty years prior and the vanquished, forcibly incorporated into it.  As CAST expanded into the stars, these issues were never solved.  Now, an alien empire is on the borders, old rivalries are rising to the forefront, and new forces from within and without threaten to upend human civilization, if not end it entirely.