This quest is not available in game.
When you are ready to proceed, let Thrall know. Follow Thrall out of Durnholde Keep and help him free Taretha and fulfill his destiny.
Speak with Erozion in Old Hillsbrad should you complete this task.
You look upon me now and see only a boy, but in my heart and soul I hide my dreams. I have plans for my people, stranger. One day, they shall overthrow their oppressors and rise as one. They will break free from the bonds that hold them and from that uprising shall be born the orcish Horde.
I promise you, stranger, should we make it out of here alive, when I have the means to reward this selfless deed, I will seek you out... I will find you.
We will leave when you are ready.