Years ago, the crypt lord Anub'arak led an army of undead warriors into the ancient nerubian ziggurat now known as Naxxramas. The Scourge forces overran the citadel, and under the will of the Lich King its corridors were transformed into a potent war machine. Dark magic tore the fortress from its subterranean home and lifted it into the sky. Hidden behind a thick layer of clouds, Naxxramas grew in strength. At the Lich King's bidding, the burgeoning wrath within the necropolis was unleashed upon the world. Brave heroes breached the citadel and eventually overcame Naxxramas' vile commander, the lich Kel'Thuzad, but the victory was short-lived.

Above the war-ravaged wastes of the Dragonblight, Naxxramas has returned with renewed fury. Kel'Thuzad, once again seated in the frigid heart of the necropolis, has laid siege to the Alliance fortress of Wintergarde Keep. As factions from around the world converge at the gate to Icecrown, the war against the Scourge enters its most pivotal hour. It is within Naxxramas that the tide of battle could turn against the Lich King... or irrevocably in his favor.