Magical Prison Quest Walkthrough
Farnirras the Pensive is imprisoned under the Lonely Barrow. To set him free, you must get inside the dungeon. Then, return to the capital and find the well in a small court, in the left part of the town. Interact with the well which is to the up left from Nok-Nok (if you have him in your squad). Get down and pick up the objects from the table, and the key you need will be among them.