In the second book of this shared-world series, the authors introduce a new Big Bad (the Astronomer) and a threat to the world -- the alien Swarm. Basically a novelized form of the cross-over "Big Event" that most comic book companies do from time to time, where some major threat affects every series in their line. This was still a great read, although you start to see the direction the rest of the series will take, as awful things happen to one sympathetic character after another.