He is a merchant, selling stolen armor, shields, weapons quietly on the street. He gets aggravated if asked about the trapdoor. Nerk can be mindread to learn that a person named Dormen is expected at the market, which allows you to talk your way in: "Where is that bloody Dormen? I've been waiting for the merchandise for a week now! Verdistis is rather far away, but the blasted lazybones should have made it before that wizard fellow put up the shield!"