Commander Lynore Windstryke at Wintergarde Keep in Dragonblight wants you to kill 15 Vengeful Geists.
The town square, down this path, is overrun with the undead citizens of Wintergarde! Our own crypt provides a seemingly endless supply of soldiers for the Scourge to throw at us. Take no pity on them, though, [player]. While they were once mortal, capable of compassion and thought, they are now ravaging undead with only one purpose: our destruction.
Venture forth to the town square and deliver the vengeful geists to their maker. Give them peace.