I read several reviews from readers who were so excited by *how much better* Spark was than Glow. I have to disagree. I thought Spark suffered from the same weaknesses Glow did--not enough interpersonal development. Ryan is fantastic with dramatic tension when it comes to plot: she can craft a great story, and she is an excellent wordsmith. But something is simply lacking in the Sky Chasers novels when it comes to her character's personal lives. I don't understand their motivations. I don't feel like I'm in their heads. The last few pages of Spark are particularly empty and rushed, and I don't understand the insertion of Kieran's mother at all. Most frustratingly, I know it's not a fault that's innate to Ryan. I just finished another of her novels, Vibes, and it's fabulous in this regard. I just don't get it. Some mild language. 3.5 stars.