Novigrad Dreaming - main quest The Witcher 3 Guide
The inn owner who hires the oneiromancer
Make contact with Triss Merigold (the Pyres of Novigrad quest) in order to unlock this quest.
Go to the house the sorceress pointed (M6,19). His owner will talk to you and tell you that the house is haunted. Walk to the first floor.
There you will meet a sleeping woman. Talk to her.
Doll on the first floor
To wake her up, you must find the source of the trouble.
Go to the attic where you will find a doll lying on the commode and a drawing in one of the lockers. Examine it in your equipment.
Walk to the lower floor and enter the room right from the bed. There's a cradle there - place the doll inside. Another drawing will appear, you will see a stove on it.
The stove can be found in the basement (the hatch under the stairs). When you interact with the stove, a cutscene will start.
The source of the trouble in the house will appear. You will have two options - make an agreement with the creature or chase it away. If you make an agreement, when you walk out of the house you can either tell the owner that the house is haunted or the truth - it will make no difference.
If you decide to get rid of the creature, you must walk to the herbalist. Buy the Burdock from him and return with it to the building.
Place it in the stove and burn with the Igni sign. The problem will be solved.
When you leave, the owner will promise to give you some of the profit from selling the house. All you need to do is visit him in a few days.
Now go back to the first floor and talk with Corrine Tilly.
She will tell you to meet her in the inn in the docks. You can go there immediately or later.
The Witcher 3 Novigrad Dreaming (Happy ending)
In the inn a seance will start. You call tell any of the chosen stories (or more than one - it doesn't matter) and answer the questions in any way you want.
Not long after that, the quest will end automatically and another one will start: Broken Flowers.