I was able to get into the area and loot the floor without getting the entire mask together (kind of found it on accident as I had trouble finding my way around-LOL).
So after looting the floor and having to fight my "employer" and her party. I finished collecting the mask peices. Is it good for anything else? There is a notation in my journal like there is something else for it to be used for. I went back to the floor area and there wasn't anything new in it after donning the mask so I don't know if I lucked out or if I broke the quest or what happened.