Eighteen stories, a third of them new, the others (1842-1992) ranging from the predictable -- Poe's ""The Black Cat"" and Ellery Queen's ""The Adventure of the Dead Cat"" -- to the seldom-seen -- Bram Stoker's ""Walpurgis Night"" (interesting mainly as the canceled prologue to Dracula), Robert Bloch's vampire fantasy ""The Cloak,"" Anthony Boucher's tidy, hard-edged whodunit ""Trick-or-Treat"" -- as well as other reprints by August Derleth (an American happens onto the Guy Fawkes festivities), Talmage Powell (candy bars spiked with razor blades), Gahan Wilson (a memorable neighborhood witch), Judith Garner (an equally unsettling little girl), Edward D. Hoch (Nick Velvet steals a pumpkin), Marcia Muller (a routine homicide for Sharon McCone), and Steven Saylor (Gordianus the Finder vs. the lemures). Of the new stories, the headliner is Peter Straub's overextended but haunting jazz gothic ""Pork Pie Hat""; but the range of the remaining stories -- Ed McBain's thuggish trick-or-treaters, Peter Lovesey's satisfyingly detailed gypsy curse, James Grady's wheels within wheels of predatory bullies, Michael Z. Lewin's sad-sack Indianapolis procedural, Dorothy Cannell's whimsical account of detection from beyond the grave -- will dispel any fears of formula, leaving only a better grade of fear behind. (Slung edited Slow Hand: Women Writing Erotica, 1992, etc. Hartman is a freelance editor.) No real peaks or valleys here: If you like the concept, you'll like the stories just fine. And the intelligently varied selection produces an anthology that, for once, is greater than the sum of its parts.