Yes, in grid map at wolf den dungeon. There should be a question mark at a block which located at 4 down and 3 right (set the top-left as a starter point). And please make sure you explore this dungeon in a right time too. I'm barely remember this but I think you must explore in by daytime.
BTW sorry for my poor English skill, English is not my first language and I don't know how to explain it well.