If this is the room right after all you get passed the room that poisons you to death (yea tough time getting through that for me), the only way to open that door is to get the Key which is on the Statue left Horn (I believe when climbing the ladder), but it is only visible if you mind-read.......and that is the part I can't remember who it was that you needed to mind read for it to be visible. Others in here may remember.
Hope this helps a little?
