Mr. Penumbra's 24-hour bookstore

Due to the Great Recession, Clay Jannon is looking for work anywhere he can find it, and his luck and ability to climb a ladder as well as a monkey have landed him the night-shift at Mr. Penumbra's 24-Hour Bookstore. After only a short while on the job, Clay realizes there is more to this store than meets the eye--even though what meets the eye is pretty incredible in itself. Several customers come in only to "check out" incredibly obscure books, as if it were a library. Thus Clay embarks on a sleuthing scheme to find out what is really going on.