In the late 28th century, the Star League collapsed and the Five Successor States were born. For the last three hundred years, these mortal enemies have fought over space, land, and politics, but now a new threat looms just outside the Inner Sphere. The descendants of an old Star League general—the Clans—have come to take what they believe to be rightly theirs. They have been bred into the best military force humanity has ever seen. The Clans have come to stay, and the Successor States must put aside their differences or face total destruction.