u need to have niss and rocca with u, got to welling village, there is a hotel there... enter it and go to the second floor, it will trigger something with niss. then go to the welling village leader and talk to him, upon ur exit there will be a fight.. after that, head to the troll cave, just before entering the cave rocca will tell u that she needs to see her father, u must head back to her village and to her father's house, u wont find him there
so talk to the guards at entrance and follow up the story from there :)