With all the supernatural things abounding, there probably is some truth to the concept of magic after all. Thus, with that in mind, you reach for the spellbook, looking for something to fix the situation you find yourself currently in.

Unfortunately, none of the 'spells' are in English, so at a loss what to do, you pick one at random, and read through it aloud, finish with the final line of Esprits des Ténèbres, je vous Commande. Révéler ce qui est Caché!

With a preternatural creak, the wall opens behind you, revealing the closed door that you never even noticed had disappeared, leading back out into the foyer. Perhaps the answers won't be found in the library, after all.