Mr. Penumbra's 24-Hour Bookstore is a novel filled with friendship, codes, history, the future, and a mystery that seems to be hidden in plain sight.
Clay Jannon finds himself in a position that is common in this economy - holding a degree in design and full of ambition, but unable to find any type of employment. An ad in the window of Mr. Penumbra's 24-Hour Bookstore catches his attention. While his list of dream jobs never included clerk in a bookstore, he went in and met Mr. Penumbra.
After a few weeks on the job, Clay begins to realize there is more going on than meets the eye. He has the night shift, the shift least visited by anyone. Strange, scholarly people come in at all hours of the night requesting books that Clay refers to as the Waybacklist. These books are not sold, but are exchanged for the one that they bring back. Clay is in charge of documenting the transaction in an ancient logbook.
His curiosity draws him into the world of Mr. Penumbra's 24-Hour Bookstore. What is going on in the store involving the Waybacklist brings Clay into a world that he can't decipher on his own. He meets new friends, draws upon the knowledge of old friends, and quickly learns who to trust and who to avoid.
As Clay and his circle of friends are trying to figure out what is going on with Mr. Penumbra and his circle, Clay depends on everything from ancient artifacts to modern technology. What he learns in the end ultimately changes his outlook on life, friendship, and love.