This is one of those books that suddenly seemed to be everywhere I looked. The title appealed and what's not to like about a mystery in a bookstore, so I downloaded it from audible.com
It is a unique book: a quirky, slightly dizzying, overlaying of Google-led West Coast Techie culture; a centuries old, secretive bibliophile sect with a mission and a real-life analog of a traditional Dungeons and Dragons questing party.
It is told with a light touch, lots of pop culture references, and a self-deprecating charm that make it an easy read.
This is a only a "thriller" if you don't get out much. No body-count. No supernatural beings. Not even car chases and gun fights. The height of excitement is a trip to an old New York basement and a visit to a massive automated warehouse and yet I was happy to keep reading.
This is a book with a message. A fairly anodyne message but one that is passionately told. I won't tell you what it is because that is about the only real surprise in the book.
Whether you enjoy this book may depend on whether you find the central character endearing and resourceful or just naive and lost. "Mr. Penumbra's 24-Hour Bookstore" made me smile but it was so gentle and so slight that it didn't make a lasting impression.
I assume that the ubiquity of the book is attributable to the fact that it has a clever title, is easy to read and envisions a MacBook-wielding, nerdy, website designer as heroic.
Reading "Mr. Penumbra's 24-Hour Bookstore" was a fine way to pass a couple of idle afternoons but if I'd bought a physical copy rather than an audiobook, it would be on its way to the second-hand bookstore by now.