I just asked like I said, give me plot summary until chapter 14, don't spoil the rest of the book. And of course when I told it what it just did it was like oh I'm sorry, here's a summary without the spoilers for the ending. So clearly it could do it without additional context.
I wouldn't expect any LLM to be able to respect such a request. Do they even have direct access to published works to use as reference material?
Also, last time I played 20 questions with ChatGPT, it needed 97 turns and tons of my active hinting to get the answer.