Bring Ur's Treatise on Shadow Magic to High Sorcerer Andromath in Stormwind.
Long ago, three mages studied in this tower until one fell to the dark arts. He was urged to turn away from that evil magic, but he could not resist. And so he was banished.
The fallen mage's new domain is the tower of Ilgalar in Redridge, and he took with him a powerful book--Ur's Treatise on Shadow Magic.
We, the mages of Stormwind, would have that book returned. Enter the tower of Ilgalar, find the tome in his library, and bring it to me.