There are five keys on my work keyring, each a master which opens a certain sort of door. Well, four of them do, at least. The fifth is something of a mystery. It opens none of the doors which it conceivably should. It makes me quite nervous. I don't want to start trying it on every door I come across in case I stumble across the Bluebeard Room, and find all my husband's dead wives. Even though I am not married, nor is this the sort of establishment which lends itself to secreted stashes of rotting women.

Bluebeard Room is a term I first came across in a Nancy Drew book (which I read as a young teenager). A search reveals plenty of references to this book, but no direct sources. From whence sprung the concept? A search for merely "Bluebeard" answers that question and provides some interesting thoughts on the legend.