What is the most resent book written by john grisham?

As of February 2023, the most recent book written by John Grisham is his 40th novel, "The Boys from Biloxi," published in October 2022.

Please note that this information may be outdated as my knowledge cutoff is February 2023. For the most up-to-date information, I recommend checking the official website of John Grisham or reputable sources such as Amazon or Goodreads.