Deliver the nightmare inducing potion to Berg in Eldfell's prison for Lennora, the kitchen maid at the tavern in Eldfell (backdoor).
To start this quest, you need to first finish the Find the Counterfeiter Quest, then go back Lennora and ask her about her grin.
You will need a high lockpick skill and a master lockpick to break out of your cell
Get thrown into prison by attacking a person and walking in front of a guard and say you want to pay it off.
Break out of your cell and unlock Bergs cell, who's cell is right next to yours.
Give Berg the Nightmare potion.
You will receive a decrease in fame.
Leave the prison by going to the Northwest corner and touch the south drain to crawl out and escape.
Go back and talk to Lennora.
The Deliver Lennora's nightmare potion will be solved.
You will receive another decrease in fame, 5 potions of Full healing, and 5 potions of Full Restore mana.