Mr. Penumbra's 24-Hour Bookstore was a wild ride, and one I thoroughly enjoyed. The premise is that recently laid off Clay is job hunting and one day wanders into Mr. Penumbra's 24 Hour Bookstore, where he is immediately hired for the late night shift. Clay soon realizes that this store is doing more than selling books; the whole back of the store is populated by books which appear in no database online or otherwise, which are regularly visited by an eccentric cast of characters who only borrow the books instead of buying them. From there, Clay is drawn into the mystery of Mr. Penumbra's 24-Hour Bookstore, and takes the reader along with him on an intriguing adventure. 
 Admittedly, the writing at the beginning is a little weird, but once you get past that (which I did--I don't think the writing really changes, you just go from viewing it as annoying to endearing) you will absolutely love this book. The characters are so wonderful and honestly my favorite part of the book. From Clay the diligent worker, to Google-obsessed Kat, best friend/patron Neel, detail obsessed Mat and Ashley, bookstore patrons and kind yet eccentric old Mr. Penumbra himself the cast is filled with intriguing characters who all work so well within their own little niches while also working well into the book's plot as a whole all while getting on surprisingly well. The mystery itself made me frantic to reach the end so I could figure out what the heck was going on, and I loved every second of it. 
 One of my favorite things about the book besides the amazing characters was the fact that technology was utilized in order to help solve the mystery. Much too often books and newer tech are pitted against each other, with people viewing things as a choice between one or the other. However, in Penumbra the exact opposite is true, and the characters readily use technology to decode the book's secrets.