This quest is given if Geralt agrees to help out Matilda right after the first part of Wine Wars: Belgaard, where he sees Matilda and her competitor, Liam, arguing over who gets Belgaard. After agreeing to help Matilda, you're given 5 tasks to complete.
The nearest one is on the other side of Plegmund's Bridge, southwest of the Prophet Lebioda Statue. Clear out the three rotfiends to finish this area. Note also that on the dead body is a journal that starts the treasure hunt quest, Don't Take Candy from a Stranger.
The second task is most likely the abandoned site, Dantan Glade, which is northeast of Fort Astre Ruins and where 2 archespores await. Kill them, and Geralt will automatically meditate and time will pass like for every abandoned site. Afterwards, you can loot one of the bodies in the cart for a letter.
The third task is rescuing the armorer west of Fox Hollow at the Herbalist's Hut. Once you take out the bandits, he'll ask for you to go with him back to Vermentino, but you can choose to stay with no repercussions.
The fourth task is another abandoned site, Pavone Slope, this time on the south side of Lac Célavy and guarded over by an archespore. Once it's taken care of and time passes, you can loot one of the bodies in the cart for a love letter.
The final task is a guarded treasure area northeast of Sansretour Valley signpost. Once you take out the two archespores here, examine the bodies, one of which has a heavy brass key and a letter on elegant stationary. Reading this letter will add the option to investigate Liam's vineyard, Coronata, for answers, or you can simply ignore it and carry on.
After completing all 5 tasks, you can either head right back to Plegmund's Bridge or, if you read the orders on elegant stationery and haven't done Liam's quest, go do Wine Wars: Coronata. Note that, if you don't complete his before turning in Matilda's, you can still collect a reward from him after finishing, but you'll miss out on an interesting ending to the second part of Wine Wars: Belgaard.
- In the duchy of wine there is nothing more important than this noblest of beverages. And when two important winemaking families began to quarrel over which would assume control of one of the duchy's oldest vineyards, all knew sparks would fly... Fully aware of the circumstances, Geralt nonetheless decided to help Matilda Vermentino deal with the troubles at her vineyard, even if this meant making Liam de Coronata his foe.
- It was not easy, but the witcher managed to resolve the troubles plaguing the Vermentino vineyard. Pleased with a job well done, he headed back to Matilda to collect his pay.
- If Geralt only helps Matilda get Belgaard:
- The witcher had helped, and the Vermentino Vineyard could bloom again. To the ducal clerk, this was proof Matilda was an able steward. He now believed she would also manage Belgaard well.
- If Geralt helped her only after helping Liam get Belgaard:
- The witcher dawdled in tending to the Vermentino Vineyard's problems. Alas for Matilda, who lost her chance to take over Belgaard, the title to which would now go to her rival, Liam de Coronata.
- If Geralt ends the feud between Liam and Matilda:
- While tending to the problems at Vermentino, Geralt had found proof that a third party was behind the troubles there. He realized this knowledge could be valuable to Matilda and Liam, and decided to share it with them both. Yet again his intuition did not fail him. Coronata's and Vermentino's owners realized they could gain by joining forces and possibly lose much by continuing to qarrel. They resolved from that day forward to cooperate - more, to form a consortium.
- If Geralt helps both before completing Wine Wars: The Deus in the Machina:
- Geralt concluded that it would be unfair of him to help Matilda alone while leaving poor Liam out in the cold. Thus he decided to resolve the problems that Liam claimed had appeared at the Coronata Vineyard. With this accomplished and with the ducal clerk doing some prodding of his own, the two young vintners concluded they would benefit more from striking up an alliance than from continuing their feud. Thus they formed a consortium and continued to produce wines under a single enterprise name.
- Solve all the problems at the Vermentino Vineyard.
- [Optional] Read the notes found at the Vermentino Vineyard.
- Inform Matilda that you've solved all her problems at Vermentino.
- Without investigating Coronata's problems, let Matilda take over Belgaard, or continue investigating and deal with Liam's problems.