In Vino Veritas is a side quest in Kingdom Come: Deliverance 2 located in the city of 
Kuttenberg. You can start it by speaking with Casper Rudolf, a wine merchant found near his cart by the Fountain on Vintners' Street.
He believes the local monastery is using a secret technique to make their wine superior and needs your help to steal their “secret” and some grape seedlings.
Step 1: Obtain the Vintner's Book
The first task is to get a book on wine, so you can make an impression on Havel the tavern keeper. Casper's book, Sir Bushek's Vintener Wisdom, is currently with his former lover, Adleta Mannlicher.
Find Adleta: She spends her days in a walled garden in the southeast corner of Kuttenberg.
Deal with Hugo: Her protective brother, Hugo, guards the entrance. You can bypass him by:
- Skill Checks: Pass a charisma or craftsmanship check - Craftsmanship is medium while Charisma hard difficulty. This is the best option - passing also grants reputation
- Combat: Duel him, win, he will surrender and then leave.
- Stealth: Climb the city wall and jump down into the garden.
Once inside, speak to Adleta. You can gain the book by passing a very hard check or suggesting you become “friends,” or by bringing her a gift of fresh flowers (which grow in the garden itself).
Best option is to be nice, tell her that the vineyard is losing money. Then choose to become friends, the next step is the dialogue skill check on the image below - pass this hard Speech check and she will give you the book. You can also ask for a kiss, which she will refuse.
Once you have the book, read it to unlock essential dialogue options for the next step.
Step 2: Impress Havel in the The Emperor Charles tavern
Go to The Emperor Charles tavern in central Kuttenberg to meet Innkeeper Havel. You need to convince him you are a high-status wine expert to get him to spill the monastery's secret.
Wear your highest Charisma gear, go to the bathhouse and consider using a Lion Perfume or Mintha perfume.
Havel will invite you to a drinking mini-game. To make a perfect impression, choose these specific answers:
- Origin: Doesn't matter
- Drinking game: Try to pass all five drinking checks. After the fifth, he reveals the secret - incense sticks.
- Best Wine: When asked about German wine, answer “Steinberger.”
- Ingredient: For the final tasting, say “ginger”
- Menu: Answer “Truly an odd menu” when he mentions a dinner he was a invited to
Alternative Path: If you fail the drinking checks or the conversation, you must sneak into Havel's office on the third floor and lockpick a hard chest to find his ledger.
Havel will reveal that the monks use a special “incense” (sulphur) in their cellars to improve the wine's flavor.
Return to Casper Rudolf and tell him your findings and he will give you 55 Groschen. You can then pass an easy speech check to also get the Kuttenberg Knight Shield. You can also give him the wine book or keep it for yourself.
Casper now wants you to infiltrate the vineyard and steal the incense sticks.
Step 3: Infiltrate the Monastery Vineyard
Travel to the vineyard located north of Kuttenberg. This section is very open and you only need to find a way to steal the secret. There are several ways on how to do this, including becoming employed at the vineyard, starting a missable Task Under the Straw Hat.
The timeline at the vineyard looks like this:
Get Hired (Optional): Speak to the recruiter at the entrance to start the task Under the Straw Hat. This gives you legal access to the common areas of the vineyard as a worker.
You can finish the whole task to get the legal access to the secret. You also don't have to really work - read our Under the Straw Hat guide for more information.
You also can just get in legally, starting the task, then steal the secret and just leave and bring it to Casper.
Steal Seedlings (Optional): Go to the backyard behind the main building (a restricted area). Locate the square plot of dirt and pick 5 seedlings.They look like this:
Be careful, as a guard and workers frequent this area, just drink a Saviour Schnapps, then go there normally during the day and locate the seedlings, then hope for the best.
Find the Secret (Sulphur Wicks): Head into the main building. Locate the kitchen and find the door leading to the cellar/storeroom. If there is a housewife cooking, you can simply sneak from the back and knock her out.
Lockpick the medium-difficulty door and search the chest inside to find the Sulphur Wicks. You can loot the barrels for some extra wine.
Return to Casper
Head back to Casper Rudolf at his cart in Kuttenberg. You can return his book and give him the Sulphur Wicks and seedlings.
In Vino Veritas FAQ
How do you start In Vino Veritas?
Speak with Casper Rudolf near his cart by the Fountain on Vintners' Street in Kuttenberg.
How do you get Sir Bushek's Vintener Wisdom?
From Adleta in the southeast garden: pass a very hard check, become friends (nicest route plus hard Speech on the follow-up shown in this guide), or give flowers from the garden.
What should you tell Havel about wine and food?
Pass five drinking checks if you can. Answer Steinberger for German wine, ginger for the ingredient tasting, and Truly an odd menu for his dinner story.
Is Under the Straw Hat required?
No. It is one way to get legal access at the vineyard. You can also use stealth or other routes described above. See the Under the Straw Hat guide for work, shortcuts, and pay.
What does Casper pay before the vineyard?
55 Groschen after the Havel lead, plus an easy Speech check can add the Kuttenberg Knight Shield.