Mr. Penumbra's 24-Hour Bookstore is a 2012 novel by American writer Robin Sloan. It was chosen as one of the best 100 books of 2012 by the San Francisco Chronicle, was a New York Times Editor's Choice, and was on the New York Times Hardcover Fiction Best Seller list as well as the NPR Hardcover Fiction Bestseller List. The US book cover, which glows in the dark, was done by Rodrigo Corral and chosen as one of the 25 best book covers for 2012 by BookPage. Mr. Penumbra's 24-Hour Bookstore combines elements of fantasy, mystery, friendship and adventure as a way of looking at the modern conflict and transition between new technology (electronic) and old (print books). The protagonist is a laid-off Silicon Valley tech worker who begins working at a dusty bookstore with very few customers, only to start discovering one secret after another. The mysterious old books, along with the store's owner, lead to a 500-year-old secret society. A prequel novelette, Ajax Penumbra 1969, was published in 2012. He was inspired to write the story after a friend misread a sign claiming the existence of a "24 hour bookshop". Source: Wikipedia (en)