"Hello, there," a quiet voice called from the stacks. A figure emerged -- a man, tall and skinny like one of the ladders, draped in a light gray button-down and a blue cardigan. He tottered as he walked, running a long hand along the shelves for support. When he came out of the shadows, I saw that his sweater matched his eyes, which were also blue, riding low in nests of wrinkles. He was very old.

He nodded at me and gave a weak wave. "What do you seek in these shelves?"

- p. 8

Warning: A large spoiler is in this review. Like, one that spoils a huge chunk of the mystery, so don't expand the spoiler cut or don't read if you haven't read the book.

Mr. Penumbra's 24-Hour Bookstore is about a young man who takes up a job as the night clerk at the eponymous bookstore, but soon discovers that weird happenings are afoot when he cracks open one of the books from the back section and finds out they're full of codes.

I found this novel to be very witty with an intriguing mystery, which are two things that I enjoy, especially when put together. Despite the characters not being very dynamic, I still thought they were likeable and fairly realistic (though, of course, I am a fan of the eccentric old bookstore owner; but who isn't?). Clay, our protagonist, could easily be someone from my own group of friends based on personality, and so could a lot of Clay's friends.

There's also a fair amount of travelling for a book in which you think you'll be spending most of the time in the bookstore. Nope, they're off to New York and Google headquarters for adventuring and to put their sleuth skills to good use. A trio of mid-twenties intellectuals are definitely not equal to Sherlock Holmes, but they get by pretty well. I only wished the stakes seemed higher during their spy time. They never got caught or got into trouble at all (except that one part, but it's resolved so easily that it doesn't feel like trouble), which makes the mystery seem a bit too easy. Give a girl some drama!

Definitely an enjoyable read for bibliophiles, computing science majors, people who wish they could work at Google, mystery lovers and nerds.