Investigate a murder mystery in the streets of Novigrad.
The Witcher 3: A Feast for Crows
This quest is a little tricky to trigger, as you have to stumble across a well-hidden corpse. Start at the Glory Gate Signpost and enter Novigrad, taking a right at the first street to trot around the circular block of buildings here. When you're on the opposite side, search around until you find a little stone bridge. Look around the grassy banks with Witcher Senses and you'll spot either a smell or the corpse itself, surrounded by crows.
Search the body for a key and then search again to find the unfortunate victim's footprints. Follow them back to a house to find three dwarven bandits looting the place.
From here you can give the key to the bandits for a small reward, or beat them up and loot the treasure for yourself.