tretoso: The mission was broken. I have to load an old save losing 20 min. of my priceless life.
Lesson learned, don't be cheap on your bribes or you can get stuck.
This mission is broken, and I don't think this explanation is clear enough. So, for anyone who is still stuck on this, here's a spoilerish explanation:
When you wake up by the harbor with a hangover, the fisherman will try to swindle some orens out of you to tell you what happened. Do *not* choose the intimidation option to get the information for free. If you do, Margot will be nowhere to be found (the quest arrow points to the street between the inn and the blue stripes, but she is not there.) and Ves will not have any dialogue options about last night. Your only option at this point is to reload your save, as from then on the fisherman has no useful dialogue either.
So, until this quest is patched (if ever) just pay the swindling slimeball the bribe he asks for. (I'm going to try and just say "bye" and go talk to Ves or Margot, see if that works. I'll post here if it does.)