Mr. Penumbra's 24-Hour Bookstoreby Robin Sloan. "Harry Potter meets Google." "Clay Jannon has left his job as a San Francisco Web designer (recession) and is now the night shift worker at Mr. Penumbra’s 24-Hour Bookstore. It doesn't take him long to recognize just how odd this store is. Its few 'customers' don't actually buy anything, but come in repeatedly examining obscure books. He decides to unravel the mystery and enlists the help of his geek friends to do so."