Wren nodded and accepted the map, "Can your spell casters place alarms on the sewer entrances in the effected wards? Perhaps something that isn't audiable, but will let your watchers know if something enters or exits the sewers during the night? That may give you something to work with if one of them... or 20 of them... are opened at night. That is the only way that I can think of transporting 20 people in relative silence without being noticed by everyone in the area." She looked at the others in the summoned party, "Unless someone else has a better idea, I would suggest we start out in the sewer system and set signs at the edges of the wards that may help us determine if they are being used. If the entrances themselves are warded, then something as simple as a thread across the passage at waist level may be enough to give us a trail to follow...I see little profit in attempting to investigate on the street as I'm sure that  the Watch has interviewed and examined as much as possible there."