There are 3 books in the Her Majesty Investigates series.
The Her Majesty Investigates series does not have a new book coming out soon. The latest book, Death at Windsor Castle (Book 3), was published in August 1998.
The first book in the Her Majesty Investigates series, Death at Buckingham Palace, was published in March 1996.
The Her Majesty Investigates series primarily falls into the Amateur Sleuth genre.