Well, there's a lot more to this fireplace than ashes and soot. In fact, this fireplace is so darned secure that it's going to get pretty frustrating before we get everything there is to get out of it. But keep reading and I'll tell you all what you gotta do.
Hint 2
First off, think a bit; haven't you seen a drawing of this fireplace somewhere?
Hint 3
On the second page of the "Letters" folder you got from Moira's safe, there's a drawing of the fireplace with letters on the stones around it. All you need now is some indication of which letters you should push.
Hint 4
You'll find that inside the "Queen Mary" book, which is on the bench next to the TV set here in the cabin. See what's written at the top of the first page?
Hint 5
So the first thing to do with the fireplace is to use the page in the "Letters" folder to spell out that word by pushing on the fireplace stones. (For Amateurs the word is "PLASTIC," and for Masters it's "OBSERVANT.") This reveals --
Hint 6
-- another level of security, and this one looks more complicated. It is.