Overall I enjoyed this one. It had some solid characters, a good story, and quite a bit of action.Bea, Quinn and Alina are the main characters in the story. I thought Crossan did a great job of weaving their stories together to get the reader to where the story needed to go. Bea is smart and tough but considered lower class, Quinn is a privileged upper class citizen and somehow they have become close friends. Bea clearly wishes for more and Quinn seems a bit clueless initially but thankfully he catches on. Alina, I'm afraid to say, is a bit of a B but she has her reasons and ultimately, it fits into the story.With all of the dystopian books coming out these days, this book has a bit of a twist that others don't have in that there is a need for oxygen tanks and based on class, availability is impacted.I am looking forward to the next book in the series as this one was well done and left me interested in learning more about the characters and what will happen next.