Sky On Fire begins with recap in the form of a letter written by one of the characters. I should have been happy about this, but it freaked me out. There are a lot of characters in these books, and I was afraid I couldn't keep them all straight. If this happens to you, don't panic. Just keep on reading. It will all come back to you in time.As Sky On Fire begins, our plucky group of kid survivors has divided into two groups: the group that wants to stay inside the Greenway, and the group that wants to head to the airport. The chapters alternate from the perspective of one group to the perspective of another.I thought that dividing the group this way worked well for the story. Most of the first book took place inside the giant Greenway superstore, and I was happy to see what was going on outside. Except that it was really bad out there. Think starving, crazy, dangerous, murderous people. The group that stays in the Greenway faces horrible things too, because they are barricaded in there with a whole bunch of food. As I was reading, Sky On Fire started to remind me of Ashfall by Mike Mullen. If you haven't read that one, it's about a huge volcanic eruption that creates mass chaos: famine, hunger, crazy people doing horrible things.These are definitely plot-driven books, and the pace moves along smoothly, with each chapter ending on a suspenseful note. By the end of the story, the two different plot lines begin to converge in an interesting way. And then came the ending. I was kind of unsure about it. I wouldn't call it a cliffhanger, but it seems like there could be more story to come. I'll post a more complete review on my blog closer to release date and link up here.