You delivered Liske's message to Gorgos, but Gorgos asked you to stay, asking you to work with him. You knew the region better then he and his Blue Fleet, he said, and your knowledge could be helpful. He asked you to get rid of the undead at the Nolantis Ruins and The Storm Circle and bring him 5 of their Thief's Marks. When you took the Thief's Marks with you and let them know where the undeads are and how they fight, they told you they would take care of the rest.