The Witch Naiara is possessed by devils. Her sister, Telissera the Healer wants you to perform an exorcism and restore her sister's health,
First Find the PriestEdit
If you find Naiara you won't be able to do much with her. In order to exorcise devils you need a priest, or rather a priest's book. The priest you need is Father Gorka in the Sunken Cemetery area.
If your Persuade skill is 51 or more you will be able to ask him about the Book of Exorcism. However he won't give it to you.
To complete the quest, you have to rob the church. You will only succeed if your Stealth skill is 36 or more. You must go at night and hit the back window of the church with your weapon. You will get the book and a few other items.
Drive out the DevilsEdit
You will find Naiara in the Stone Village (see map). If you have the book and your Persuade skill is above 50, you should be able to complete the exorcism. She will give you a ring to take to her sister the healer.
If you see the healer again, she will reward you. You will also receive Naiara's Ring (Fortify Magic 30%).