Not a concrete one, just bricks with crumbling mortar. That's what I smacked into on novel. It's simply a matter of figuring out one last thing. One simple little thing is all that's between me and the end of the book. Three and a half pages of new notes and I'm no closer. These are the kind of notes that are open conversations, asking questions, seeking unexpected answers, free-writing, exploring the remaining plot hoping something will click and the solution will appear.
In other words, finding fifteen different ways of asking the same question and still getting no answer.
However, I did get one action sequence out of all that note-making that I hadn't anticipated. One of those satisfaction-guaranteed "I believe we have some unfinished business" scenes between two characters. Heh-heh. It's something, at least.