From time to time I see complaints on various blogs about how too many modern mystery readers (as well as some writers) seem to have no sense of--or much respect for--the writers who've gone before.
H.R. F. Keating is a distinguished novelist (the Inspector Ghote stories for just one example) and critic (for years he reviewed crime novels for the Times of London) who has written a book that is a graduate study course in the history of mystery. In one hundred thoughtful--and sometimes brilliant--short essays he traces the mystery from Poe to the late eighties and P.D. James.
This is a sleek, witty, rich travel guide through examples of every kind of mystery, from Christie to Wambaugh. With pieces on, G.K. Chesterton, Mary Roberts Rinehart, Dorothy L. Sayers, Rex Stout, Ngaio Marsh, Margaret Millar, Ed McBain and many, many others Keating touches on the themes, styles, trends of every decade from 1868 to 1986. You may not want to read every single book Keating recommends but the essays you will give you a helpful, historical sense of the mystery's evolution over more than a century.
I've mentioned before that Keating is so good a stylist, he's fun to read just for how he shapes his sentences. He also has his own slant on writers. Much as I admired Julian Symons his own collection of opinions (Bloody Murder) cost me a couple of molars from grinding my teeth. Keating is more gracious; he finds the most interesting book in a writer's bibliography--not always the most popular. He never offers us a bad book just so he can score points.
"Indispensable" is rarely used appropriately but it certainly applies here. If there is one book that belongs on the shelf of every mystery reader, this is it.