There are 4 books in the Bartlett and Boase series.
The Bartlett and Boase series does not have a new book coming out soon. The latest book, The Proof of the Pudding (Book 4), was published in April 2018.
The first book in the Bartlett and Boase series, Empty Vessels, was published in March 2014.
The Bartlett and Boase series primarily falls into the Mystery genre.