A New York Times bestseller, Mr Penumbra's 24-hour Bookstore is an entirely charming and lovable first novel of mysterious books and dusty bookshops; it is a witty and delightful love-letter to both the old book world and the new Recession has shuffled Clay Jannon out of his life as a San Francisco Web-design drone - and serendipity, coupled with sheer curiosity, has landed him a new job working the night shift at Mr. Penumbra's 24-Hour Bookstore. But after just a few days, Clay begins to realize that this store is even more curious than the name suggests. There are only a few customers, but they come in repeatedly and never seem to actually buy anything, instead they simply borrow impossibly obscure volumes from strange corners of the store, all according to some elaborate, long-standing arrangement with the gnomic Mr. Penumbra. The store must be a front for something larger, Clay concludes, and soon he's embarked on a complex analysis of the customers' behaviour and roped his friends into helping to figure out just what's going on. But once they bring their findings to Mr. Penumbra, it turns out the secrets extend far outside the walls of the bookstore...