While I haven't read this book, I read Kate O'Hearn's earlier series, Pegasus and I enjoyed it very much. It's about a girl who lives in New York City. Her life is very normal until one night during a horrible thunderstorm the mythical horse Pegasus lands on her roof, injured. She is thrust into the war between the Olympians and a race called the Nyrads. This is an interesting set of books, combining Greek mythology and science fiction elements into a miraculous read.