A fascinating novel about book lovers, data lovers, good old-fashioned printing and a mysterious organisation. It begins with Clay, the main character, taking a night job at Mr Penumbra’s intriguing 24-hour bookstore, a place where hardly any customers come in and, when they do, only borrow obscure titles. The place is tiny and vertical. Clay has to climb huge ladders to find those mysterious books. What better start for a story?