This book was first published as “A Mind Diseased”, which made it difficult to find, as I was trying to find Markham #4, "Crime in the Hospital". A very annoying habit of authors and/or publishers to bring out a book under several titles. Not exactly a recommendation in my book.
The story is well plotted, and well written. Fortunately less of the catholicisms, and fortunately a little less of his girlfriend. She did have a bit of a front row seat in the first three books, and this makes the whole better balanced. This time we find our intrepid duo (or sometime quartet) in a mental hospital, or in Noakesies parlance a looney bin. It takes a while, and DI Burton gets seriously threatened, but all ends well.