A mysterious invading force strikes the coreward region of the Inner Sphere. The invaders, called the Clans, are descendants of Kerensky’s SLDF troops, forged into a society dedicated to becoming the greatest fighting force in history. With vastly superior technology and warriors, the Clans conquer world after world. Eventually this outside threat will forge a new Star League, something hundreds of years of warfare failed to accomplish. In addition, the Clans will act as a catalyst for a technological renaissance.