Fiefdom of the Crystal Skull
But, you'd expect this kind of preparation from somebody who wrote The Bond Files: The Unofficial Guide to World's Greatest Secret Agent. Paul asked informed -- and sometimes difficult -- questions. Like, my reaction when I learned that the title for Indy IV was "Kingdom of the Crystal Skull." I don't think he'll be able to print my answer, at least not verbatim.
He also asked me what it was like to create the backstories for Belloq and Sallah (that was fun), and which of the novels was my personal favorite (HOLLOW EARTH). He also asked if I meant what I said about passing the hat and whip in the afterword to the last novel.
Yep, I meant it.