Please note: I don't review to provide synopses, I review to share a purely visceral reaction to books and perhaps answer some of the questions I ask when I'm contemplating investing time and money into a book.
This is an odd little addition to the Laundry Files canon. It clocks in at 74 ereader screens; it's hardly long enough to get a story going, let alone developed and resolved. There's a very long setup and then a super quick resolution which left me just a little puzzled - I won't give anything away but I feel the solution to the problem isn't consistent with the "rules" of the Laundry Files world. We did learn some more arcane trivia about the history of the Laundry, but we didn't learn very much about Bob Howard and the "mystery" aspect of the story leaves some huge gaps that aren't adequately explained. That being said, the writing is crisp and elegant which I appreciate after the clumsiness of The Rhesus Chart. Finishing this brings me completely up to date with the Laundry Files series, which as you can appreciate is always a bittersweet feeling.
A weak 3.5; it was enjoyable enough for fans of the Laundry Files but doesn't offer very much for people just coming into the series.