As book two in a series, Spark really hits the ground running. Once again, the plotting in this book really stands out. Multiple third person POVs aren't typical in YA, but the fact that Spark alternates between Kieran's, Waverly's and Seth's point of view worked well for the story. Since the three of them are all at odds and operating at cross-purposes, this narrative technique added a lot of suspense by allowing the reader to know what each of them was up to and why.I also loved the fact that Amy Kathleen Ryan really delves into the moral implications of her characters' choices and shows the consequences of their actions. There aren't obvious heroes and villains here -- or when you think there are, you soon change your mind. Spark centers around Kieran's struggle to maintain order on the Empyrean, and the concurrent search for the saboteur aboard ship. Seth, Kieran and Waverly are constantly butting heads in a way that made this feel way more interesting than the usual love triangle. When the devious Anne Mather (awesome female villain!) wants to negotiate peace, the kids have to decide how much they can trust her, and what they are willing to risk to be reunited with their parents.Read Full Review on my blog!