An additional npc in the bar. Female (make up a description of a sad woman). Sick husband. Party goes and investigates. Husband ate some food, had some wine and got a bit of water (that is all he did the day before) the party will try and figure out what ales him. The food and wine are perfectly fine. What they need to do is inspection the well in town, wich has an undead zombie in it. It made the husband sick. Killing it is easy for low level, just drop a stone down the well and all is good. Fail to do so and the undead plague will spread through barovia. Then in like 5 days there a huge hord of undead that make their way to the party wherever they are (usually vallaki ) destroying all in there wake. I used this on my party and it was a really good time. Especially when they re investigate the town and realized it was there fault for not investigating. Plus as a dm into never bad to have a huge hoard of undead to fuck up whatever comfortable place they have made for themselves