Mr. Penumbra's 24-Hour Bookstore (2012)

This winning literary adventure, Mr. Penumbra's 24-Hour Bookstore, has all the elements of geek hipsterdom: fantasy novels, role-playing games, computer coding, and classic typography. Clay Jannon goes to work at a mysterious San Francisco bookstore that's an outpost for a scholarly cult, then recruits a high-tech posse to crack a 15th-century code. Despite occasional stumbles — it's best not to overvisualize computer-hacking sessions — Sloan grounds his jigsawlike plot with Big Ideas about the quest for permanence in the digital age. B+