Mr. Penumbra's 24-Hour Bookstore by Robin Sloan

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.