One of his well - known novels is 'The Firm'. It has a complex plot that could make for some interesting crossword clues. For example, the main character Mitch McDeere could be a clue, and the answers could be related to his actions, like 'lawyer who uncovers firm secrets' or something similar.
I'm not sure exactly which is the latest one. But you can find out by looking at recent book reviews, visiting popular book-selling platforms, or following John Grisham's social media accounts for updates.