There are 4 books in the New Lord Peter Wimsey/Harriet Vane series.
The New Lord Peter Wimsey/Harriet Vane series does not have a new book coming out soon. The latest book, The Late Scholar (Book 4), was published in June 2014.
The first book in the New Lord Peter Wimsey/Harriet Vane series, Thrones, Dominations, was published in February 1998.
The New Lord Peter Wimsey/Harriet Vane series primarily falls into the Amateur Sleuth genre.