Hm, I'm kind of stuck.
Explored every availlable room.
Only possible way I see is behind this wall:
http://www.directupload.net/file/d/4507/7k25tw5c_p...
However I don't know how to get rid of it :-/
Explored anywhere else many times but there simply is no other way. O_o