The latest in a long line of chatty demi-reference books for crime mavens (cf. Steinbrunner and Penzler's Encyclopedia of Mystery and Detection, Barzun and Taylor's Catalogue of Crime, Dilys Winn's Murder Ink) is as irresistible as its forebears. Its 128 essays and lists, mostly of a few pages or less, cover everything, or almost everything, from regional mysteries (despite no mention of S.K. Epperson's Kansas gothics) to such subgenres as cozies, dark suspense, gay detectives, TV mysteries, and true crime (though there's nothing about courtroom drama, perhaps for legal reasons). Most of the name- brand authors (H.R.F. Keating, Joan Hess, Lawrence Block, Stephen King, Douglas G. Greene, etc., etc.) write with affectionate, often casual mastery; and though no collection this big or broad can hope to maintain a uniform standard throughout--historical glimpses of Doubleday's Crime Club imprint and Alfred Hitchcock's Mystery Magazine are disappointingly perfunctory--fans impatient with the authors' occasionally cheerleading tone (``If you can't find a Texas author's book to suit your taste, you just aren't trying hard enough'') can find fresh vistas by turning a page, especially if they land on one of editor Breen's useful thumbnail sketches of a subgenre or one of the editors' endlessly arguable lists (``The Ten Most Underrated Mystery Writers,'' ``25 Notable Noir Novels,'' ``50 Great Gold Medal Crime Classics''). Despite inevitable blemishes: a truly indispensable volume.