Second book in the series. The point at which things start getting seriously complicated — i.e. I feel like this is Stross writing SF, rather than sticking to the bounds of the urban fantasy genre he was aiming at when the series began.
There's some slightly odd pacing here, especially in the first book (perhaps influenced by finding out that he'd have to head for a cliffhanger rather sooner than expected, going by his retrospective?). As a whole, though, this works well; it's an engaging setting, and it lets Stross explore some interesting political questions.
ISBN 1447237625.