This novel carries on from book 1. It shows how Cal begins to develop a strategy to fight back. Suddenly his nerdy interests are exactly what are needed, but he cannot do it alone, and his autistic nature makes finding allies difficult.
We also see Kim's journey when she wakes up after the apocalypse and her brutal awakening into how fast any semblance of law and order disappears.
Cal and Kim's paths are destined to collide, but will they be able to work together, each one overcoming their natural reticence?
This novel concentrates on the relationship between Cal and the various people he needs to help him fight back against the CUG. It also shows Cal planning an audacious attack, which seems almost impossible. At the end of the novel, all the plans seem to be falling to pieces, and so another cliffhanger leads into the third novel in the series. If you have got this far, it is difficult not to continue with the next novel in the series.