Hm, let's see, we have this number 13. People call it a horror number, for some it's a lucky thing, for other people it is kind of "mysterious", maybe religious. And we have suggestions like "pirates" and "casino".
Themes which have to much "real crime" in it, aren't the best ideas, in my opinion, because we had this last EF.
So I guess I vote for "pirates" and "mysterious stories", if you want so. But it have to be something with this number, 13.