The video above is the The Witcher 3 Wild Hunt Deadly Delights Witcher Contract Quest Walkthrough and shows how to complete Deadly Delights, the quest featured in The Witcher III: Wild Hunt.
The video walkthrough covers the following objectives:
Talk to the guard. Get information from the medic.
Examine the crime scene.
Follow the tracks.
Talk to the brothel owner.
Follow the scent of perfume.
Talk to the man who is acting strangely.
Find your way into the house.
Confront the succubus.
Collect your reward from the guard.
