They found an abandoned church of some extinct carpenter-god (Dead-god is a district of the city, all abandoned temples, mosques and churches). They watched for a while, watching the comings and goings. Dead-god is where the fading aristocracy mostly live. They watched squires buying for their knights, ladies in waiting buying for their ladies, knights buying for themselves, and so on. This was a higher end redcap dealer and once you knew what you were looking for, it was obvious the traffic in and out that drugs were being sold.