Edgar Cantero's thriller "The Supernatural Enhancements" is the latest entry in the centuries-old narrative device that is the epistolary novel. The device, where a story is told via a montage of variably trustworthy letters, journal entries, newspaper clippings, etc., been used by many authors to better effect. (Stoker's "Dracula," Shelley's "Frankenstein," and Collins' "The Moonstone" are a just a few classics that leap immediately to mind.) Cantero's effort to tread in those well-worn footprints is not an abject failure, but readers are justified wondering why the author elected to tell the story this way. The plot and setting, and the characters that populate them, are all sufficiently intriguing to hold interest on their own merits without resort to gratuitous epistolary gymnastics. Cantero's choice of narrative technique detracts, often materially, from what could otherwise be a solidly gripping paranormal mystery.