Without a Trace - Novigrad (Hearts of Stone)
Location: Brunwich - Herbalists Hut/Erde
Quest Giver: Brunwich's Notice Board
Other Requirements: Hearts of Stone DLC
This quest begins by accepting the contract off of the Brunwich's Notice Board. For this quest the first thing you will need to do is visit the Herbalist at the Herbalist hut (pictured above) who will fill you in on what you have to do for the quest. Once you've spoken to the Herbalist head to the quest marker on your map.
Here you'll find a wagon that glows red in the northern portion of the quest circle just south of the town of Erde. Next to the wagon you'll find a blood trail that leads north to Erde where you'll find two old people that you can speak with (pictured below) you're able to ask these folks about the herbalist you're looking for but they won't tell you much.
At this point in time your quest updates and sends you back to the Herbalist who began it... But there is actually more we can still do. On the path that is literally right next to the old couples house Geralt will get a whiff of rotting meat in the air. This will update your quest as well as give you a scent trail to follow.
The scent trail leads a very short distance to a cellar door with a bunch of debris piled on top. Use Aard to blow the crap off the top of the cellar door and head inside. You'll find Folkerts body in here all chopped up. Now you'll have to return to the couple and question them about what you just found (pictured below).
You'll have two options, you can either tell them to swear they'll never eat another person again or kill them. Depending on the option you choose, returning to this village at a later time will give you a few different outcomes. I've listed each of them below.
Kill the Couple: Alghouls will be at this village instead of the old couple
Told Otto the truth but let the couple live: Alghouls will be at the village when you return too, Geralt will remark that Otto probably killed them
Lied to Otto and let the couple live: The husband will be grieving as his wife has recently died from hunger