Desperate for a job, art school graduate Clay finds himself employed at Mr. Penumbra's bookstore. The bookstore is an odd place, with a limited selection of books, but in the back, the shelves are crammed with a large collection available for loan to a small group of people. Clay is forbidden to open the books yet required to describe the borrowers in great detail. Late-night boredom catalyzes curiosity, and soon Clay discovers that the books are part of a vast code. Edgy and whimsical, Robin Sloan's Mr. Penumbra's 24 Hour Bookstore is chock full of young love, rollicking adventure, and global conspiracy, a a good measure of paper books vs ebooks.