The erinyes takes a leap off the edge, soaring back to the third layer, and this gives Alaedra a chance to look around. She really does have no option other than to enter the city-castle, it turns out, as it is surrounding the hole. Presumably, any wilderness lies on the other side. Fortunately, there are gates that are open and do not seem to be guarded. Others, probably to specific towers or wards, are locked, and have both bearded devils and giant, winged, almost draconic fiends standing guard.