Monument 14: Sky on Fire is about Dean and his brother, Alex. Dean and Alex trade narration each chapter. In this book Dean is staying behind with Astrid and a few other kids. They have survived the chemical leakage and are trying to wait out the chemicals. They have to work together to protect the other kids from the military, disease, and most of all, from themselves.
Alex is traveling to an airport to be airlifted out of the U.S to escape the disease, but they are interrupted by military troops that take over their bus. The remaining kids walk the rest of the way on foot to the airport so they can find help for Dean and Astrid.
This book, like the previous one, has tons of action and tons of surprising moments. I liked thus one just because it had the more survival based fell than the first. I would recommend to a higher age for inappropriate scenes.