The Night Shadow Clan castle is to the east of the Web Wood Forest, after you get to the second map head North. The castle will be visible soon enough! After speaking with the court Witch within the Night's Shadow Clan castle, she tells you to travel to Crovinale, the town North of the Web Wood Forest, to find a Necromancer. You must kill him and return to the Court Witch, she'll send you on your next quest.
I'll be able to look further into this tomorrow (Yay alcohol!) Anyways as far as I can tell, this is the quest line you are on. The witch is located at the eastern side of the castle by the blacksmith!
Thank you,
Talon
BTW: Mikheli made a video featuring Valcarta II: Awakening's new enemy art! Take a look:
http://www.youtube.com/watch?v=HAWmLJJD3Tw