Effect: From a bunch of books a book is chosen, any page is opened and any passage selected. The spectator is asked to read that passage and remember what is happening. The whole time the book is handled by the spectator and his choices are completly free. The book is ungimmicked. Then the mentalist recites from the spectator's mind the exact content.
Method: Force the book of choice to that one spectator. That is the easy part. Here is the hard one... before the show you actually remembered all the content of the book. Each passage must be memorized. Now you are set and the rest should be obvious.