Here's a mystery for you: What is it about South Florida that seems to sprout mystery writers? Do they come here as poets and experimental novelists and turn to the mystery-and-murder genre after hearing of bodies wrenched from the muck of the Everglades or loads of cocaine or human cargo found in the belly of cargo ships? Or is it the heat of the climate that makes for murderous thoughts? It's interesting that one of the few independent bookstores to survive the Bordering and Barnes-and-Nobling of the book business is a niche store specializing in mysteries and suspense. Owner Joanne Sinchuck, who moved Murder on the Beach from South Beach to Delray Beach in December 2002, stocks a wealth of Florida mystery writers, including Edna Buchanan, John Lantigua, and Carolina Garcia-Aguilera. And the store hosts weekly discussions, author signings, and such.