"This female drow is the mysterious and enigmatic leader of the large Underdark army that threatens Waterdeep. The Valsharess (which means Empress in the drow tongue) is the title she has given herself her true name still remains a secret. Through force and diplomacy she has melded together the enemies of her people into a massive army that threatens to topple the most powerful city in Faerun. Little is known about her except that she and her forces have mastered an advanced form of fire magic. She is intelligent, proud and more than certain of her ultimate victory."
The game begins with the Valsharess learning of the prophecy of the surfacer who is destined to stop her. After the hero rescues Halaster from the drow in Undermountain, Halaster places a magical geas on the player, forcing him/her to do his bidding and kill the Valsharess. The hero's hunt for her culminates after the drow invasion of Lith My'Athar. Upon her army being pursued to her keep, the Valsharess commands the archdevil Mephistopheles, whom she had earlier bound to her service, to teleport the hero into her courtroom, where she traps the hero within a magical barrier and then orders Mephistopheles to kill him/her. Mephistopheles, in turn, defies her order, killing the Red Sisters in the chamber instead and releasing the hero from his/her prison, allowing him/her to defeat the Valsharess.