What is the next Joshua files book called?

There isn't a "Joshua Files" book series! It's possible you're thinking of a different book series or that you've misremembered the name.

Could you please provide more information? For example:

* What is the genre of the series? (e.g., fantasy, mystery, sci-fi)

* Do you remember any of the main characters' names?

* What is the general plot of the series?

With more information, I can help you find the book you're looking for!