There are 3 books in The Birthgrave Trilogy series.
The Birthgrave Trilogy series does not have a new book coming out soon. The latest book, Quest for the White Witch // Hunting the White Witch (Book 3), was published in February 1978.
The first book in The Birthgrave Trilogy series, The Birthgrave, was published in June 1975.
The Birthgrave Trilogy series primarily falls into the General Fiction genre.