A Barnful of Trouble - Novigrad
Quest Giver: Peasant
Other Requirements: Complete this quest after accepting it; if you leave the Ghouls will break out and kill the villagers
This quest begins in the town of Carsten which is found in the southern portion of Novigrad. When you arrive in Carsten you'll find a group of villagers (pictured above) surrounding a barn with loud noises emitting from it. Approach and speak with one of the villagers to begin the quest. If you're having trouble locating the town of Carsten, use my screen shot below for further guidance.
For this quest all you need to do is defeat four Ghouls - the villagers will barricade you into the barn until the Ghouls are defeated - then speak to them to turn in the quest. It's as simple as that. You can inspect the bodies that the Ghouls were eating before you entered the barn if you wish - it'll give you an extra dialogue option with the villagers at the end of the quest.