Apparently we had more content than I expected, so our latest game ended up with the entire session being the wrap up of Chapter 4, rather than just the start and then beginning of Chapter 5. However, this did allow for the group to explore much more of the mysteries of the giant city, which manages to fill in a number of gaps in the overall plot, which proved very beneficial. In particular, since we have been playing this particular campaign for over 2 years, many of the original details have been forgotten. This allowed for a refresh of the history of the Runelords, their actions, and the current view of their mythology. As a result, I think the group is much more motivated now to move on to Chapter 5, where they start to figure out a means to stop or defeat the return of the Runelords.