Though Lady Sylvanas and the Forsaken finally took vengeance upon their hated enemy, The Lich King, their dark crusade in Northrend proved costly. Betrayed by Grand Apothecary Putress at the Battle of Wrathgate, the Forsaken's devious plague of death was unleashed upon both the Alliance and Horde to calamitous effect. Unbeknownst to Sylvanas, Putress and his demonic ally Varimathras had taken control of the Undercity. As a result, the Forsaken were wrongfully blamed for the traitors' atrocities. Though the Undercity was eventually retaken, Sylvanas and her followers still bear the weight of Putress' sins. Mistrusted by the other members of the Horde, the Forsaken must now prove their loyalty to the cause and redeem themselves from their supposed treachery.
To this end, Sylvanas has bolstered her defenses within the Tirisfal Glades and readied her undead forces for any contingency. As one of the forsaken, you must use your cunning and viciousness to slay any who would pose a threat to Sylvanas's rule. Be they human, undead, or otherwise.
- in-game voice-over