I'm not sure what I'm doing different than others. I have a knife & key, and entered the broken window to the library basement. Can't climb back out, and there's an empty spot on the bookcase that the character shrugs at.
That's weird. Don't you have a book in the inventory? The one you get right at the start of the game? If not, it might be a bug and I would advise you to restart the game. Sorry for the inconvenience. Did this happen after loading a saved game?