La Cage au Fou Main Story, Blood and Wine Quest

1. Meet Regis at M?re-Lachaiselongue Cemetery.

The Beast's and Geralt's clash had been violent albeit brief. Now With it done, Geralt could have a chat with his long lost friend Regis. A higher vampire, Regis revealed that the creature terrorizing Beauclair was none other than his dear friend Dettlaff. Geralt now understood he was pursuing a truly dangerous foe - a higher vampire, one of Regis' ilk. Then the witcher and the vampire heard a clamor. A posse was drawing near. So Geralt and Regis cut their conversation short. Preferring not to draw any attention, the vampire disappeared, but not before inviting the witcher to pay him a visit at temporary quarters he'd established at the local cemetery (you had better believe it!), Mère-Lachaiselongue.

2. Find a way into the crypt.

Main doors are closed, you have to find another way into the crypt. Find an open grave and go inside. In the tunnel you will have to kill a few kikimore workers (37).

Regis is in the main chamber. It's time for a long conversation with your old friend. He will expain you what to do, if you want to find Dettlaff. You have to brew a special decotion, and you need a special ingredient to do it. To get one, you have to visit abandoned residence in the Caroberta Woods.

3. Look for the wight's lair.

Geralt paid Regis a visit at his cemetery hideout. After a long debate, the two old friends concluded their first order of business was to find Dettlaff. Regis was to prepare a concoction to aid them in this endeavor. Called Resonance, said brew required an array of ingredients, many of them hard to find. One such component was the saliva, or salivary glands, of a spotted wight, a species thought to be long extinct. Yet it seemed that one specimen remained alive, having made its lair near Beauclair. Geralt set out to find it.

4. Use your Witcher Senses to search the wight's lair.

One of the spoons in the house is a special one, it's some kind of a key - Spoon key, and it has Spoon-key note attached to it. Looting it will add a new quest to your journal - Spoontaneous Profits!.

If you want to be able to remove the curse from the wight lining in the house, then you have to examine smashed mirror, read Decaying letter, read Stained diary, examine table and skeletons, examine dining table in the basement located next to cauldron. It will be active when Geralt pronounces the following sentence:

Wight that lives here - definitely afflicted by a curse. And it's been trying desperately to lift it.

Smashed mirror.

Decaying letter.

Stained diary.

Table and skeletons.

Dining table in the basement.

5. Find the wight's cauldron.

Cauldron is in the basement.

6. Look into the cauldron.

7. Hide in a place with a good view of the cauldron.

Hide in a wardrobe.

If you activated an option to remove the curse, then you will be able to make a decision: attack the monster or try to lift the curse.

If you decided to try to lift the curse then you will receive Wight brew and will have to make one more choice. If you want to succesfully remove the curse then you have to select third option: 

Let's eat, not using the spoons.

The first and the second options won't remove curse, but you don't need to kill wight becouse you already have Wight brew.

8. Follow the wight.

9. Report back to Regis.

If you killed the monster then

Geralt found the spotted wight at an old, abandoned estate. The witcher slew the monster and, its salivary glands in hand, made for the cemetery.

or when wight is alive (i.e. if the curse has been removed)

Geralt found the spotted wight at an old, abandoned estate. The witcher chose not to fight it, opting instead to hide in a wardrobe and await his chance, though how it would come, he could only guess. Once the wight had come and gone, Geralt collected its saliva, which the monster had added to the brew it was making in a large cauldron.

10. Talk to Regis when you're ready to go.

Once Regis received the penultimate ingredient required to brew Resonance, he said the time had come to tackle the most difficult challenge. For apart from all else, Resonance had to include the blood of a higher vampire. At first, Geralt saw this as no challenge at all, as standing before him was a representative of said species. Yet Regis revealed that the blood he needed had to have a specific chemical composition. His blood would change only under conditions of great suffering. Regis offered to endure this without hesitation.

11. Follow Regis.

On your way down you can find full set (six parts) of Tesham Mutna Gear.

12. Place bait in each of the four tunnels. 0/4

Use aard sign to destroy barrels, etc. blocking two spots.

13. Tell Regis when you're ready to fight.

14. Kill monsters until bloodlust transforms Regis into a monster.

You have to fill a bar at top of the screen.

15. Quest completed.

It proved quite the ordeal for Regis, a sacrifice one might say. But they obtained the last ingredient required for Resonance, and the vampire could prepare the concoction. Geralt drank a dose, and visions ensued. He saw Dettlaff, where he had recently been, what he had done. It was enough for Geralt to know he now needed to find a local bootblack. He hoped the boy would help him locate his foe.

Next / new quests are The Hunger Game (Secondary Quest, Blood and Wine), Where Children Toil, Toys Waste Away (Main Story, Blood and Wine), Spoontaneous Profits! (Treasure Hunt, Blood and Wine).