A Feast For Crows - Novigrad
Location: Novigrad/Gate of the Hierarch
Quest Giver: Acquired Upon Finding An Item
Other Requirements: Visit Cleaver during Get Junior
You can begin this quest after having your meeting with Cleaver in a shop near Hierarch Square during the Get Junior Quest in Novigrad. While traveling through the southeastern portion of Novigrad just northeast of Gate of the Hierarch Geralt will comment on the smell of decomposing flesh. In this location you'll want to use your Witcher Senses to follow a scent trail to a body.
If you're having trouble locating this area use my screen shots above and below for further guidance. The Scent trail you have to follow is very easily found by using your Witcher Senses - just search in the area you see me standing on my map below.
Once you've discovered this quest and acquired the key you will need to follow the blood trail to a nearby house which is where you'll find Cleaver's Men. Since you have the key and the dwarfs want it they'll tell you to give them the key and no one has to get hurt.
At this point you have two options, you can tell the little buggers to piss off and you don't like being threatened then proceed to make mince meat out of them... Or you can give them the key, receive a measly reward of 20 Crowns and leave. If you decide to take the mince meat route once you're finished with the dwarfs go upstairs and pillage the house - then leave. You'll find a bunch of Crowns and Florens upstairs.
Regardless of your choice the quest will complete here.