Where can I get the quest with the vampire from the trailer? (The Witcher 3: Wild Hunt)

Are you talking about the vampire in the coffin? Then in the dungeons of Novigrad. I accidentally found the entrance to the dungeons myself (some other task will lead you into them), and I ran there with a witcher's flair. You will climb into one of the hidden rooms, there will be an archaeologist near the coffin, he will start the quest.

there are already a lot of threads on the forum