Have to admit I had a heck of a time with that arc as well. Without giving to much away there are two people you need to talk to who's stories don't quite match up to. Also you need to go back to Morganna (sp.?), and get her to open another room for you to get more info, on to how to complete it.
If you must there are walkthroughs on Google that would make the hints more plain. But, I think that should be enough info.