If you can't find it at this mystery bookstore, well that's a real mystery.. In Short New and used, hardcover and paperback, the books go on and on in this plain-vanilla store hidden in back of its sibling, Uncle Hugo's Science Fiction store. The shelves are packed, a two-paperback stratum shoved horizontally atop every row. Everything is in its place: Old Detective Book Club three-in-ones, Ellery Queen's Mystery Magazines and a bright-blue swath of Hardy Boys marking the juveniles section. Cardboard flags identify Edgar and Shamus award-winners among the new titles.