Invaders from beyond the Periphery, the Clans have beaten the forces of the Inner Sphere repeatedly. Now the Clans are driving toward their ultimate objective-Terra, cradle of humankind, and hub of the ComStar communications network.

Nothing the Inner Sphere has can stop them. The heir to the throne of the Draconis Combine is missing. Whole regiments of BattleMechs lie smashed like abandoned toys. Rasalhague is overrun. The Clans are sweeping toward the center of the known universe in a relentless tide.

Humanity's only hope is the Inner Sphere's most powerful traitor. ComStar betrayed the Inner Sphere by aiding the Clans in their conquests. Now the mystic sect that controls all interstellar communication must face the Clan hordes alone. And a mysterious, elderly warrior along with the untested warriors of ComStar is the Inner Sphere's last defense against total defeat