Solution will contain story details.
*** Spoiler - click to reveal ***
When you get to the encampment the first time, after escorting Rook there for the quest "upon a pawn". Return to the starting town Cassardis and find Madeleine in the inn. You will have to escort her to the encampment and give her a a 1000 g when she ask for it. Next after getting to Gran Soren and completing the main quests "A Matter of Myrmidons and Lure of the Abyss" you'll find a npc named Mason in front of the inn and get the quest "Chasing Shadows". Be careful not to get spotted and after completing it leave gran soren and comeback. Speak to her at her shop where the abandoned house was. Do these quest as soon as you can because they can disappear with the progression of the main story.