Wanted: A rigged book with a hollow interior
A staple of mysteries. It looks like an old thick book. But you open it and fifty pages in there a deep hole in the rest of the pages. What's in the secret pocket? That's the fun.
Rigged to open and close is important so that the look of the book on a shelf and the look when the detective opens it is the same.

Comments
So something like this, but where the right half had a hole?
Yes. A big rectangular hole. Not necessarily a bible, but that's a nice touch. In movies, it's usually well worn book no one would want to open randomly. :)