This kindle novella is a prequel to the entire Iron Druid hexology (well, at present it's a hexology - although my latin is shaky, so maybe it should be sexology. Or is it my greek that's shaky? Anyway, at present its 6 books, with the 6th coming out in a month or so*). It is set before the events of Hounded, pre-Granuile, but still with Attticus' henchdog Oberon. Its actually nice to see this little flashback to the old bookshop and a more relaxed Atticus, and then get to see him dealing with ancient Egyptian gods, black sorcerers and animated sarcophagi. There is action, humor and a wisecracking dog - and the scene where Atticus and Oberon try to evade a large posse of cats just steals the whole book.
If you are toying with reading some witty urban fantasy, and have decided to give Iron Druid a shot, its worth starting here, actually. It's a pretty good sample of what the writing and story is like, and it is, in fact, the chronologically first entry in the series - and the price is right. There is nothing here that is a spoiler for anything else later on, and it's a nice little read while you are at it.
* - Endnote: its actually 6 and a half books, with me completely forgetting the other kindle novella Two Ravens and One Crow. But since I have no idea what is short for trilogy plus a half, you can bet I have even less of a clue what six and a half books might entail. Or, I suppose, 6 and two half books if I count this.