(The devs already know about this, they chuckle about it on forums and said it's a low priority in the fix-it-queue.)
You get the quest in Gath Fortnir, the free-people's refuge in Himbar, Angmar. You are supposed to free slaves in Carn Dum. However, you can port to the Shire, go to Waymeet, and speak to Dora. If you have done her chicken rescue quest (5) before, you cannot do this. If you have not, run north up the road to her farm and start picking up chickens. Each time you pick one up, a message tells you that you have freed a slave from Carn Dum. The quest calls for 3 chickens to be rescued, so you must cancel the quest and re-start it to get the other two. :)