Faceless is the third book in the Nameless series. You should read Nameless and Heartless before starting this book.
As in the previous books, Faceless revolves around a magical family of cousins (and their significant others). All of them are young people, and most are starting to put together a framework of how they think they want the rest of their lives to work out.
To me, one of the things that this book is about is that the choices people make – out of love, or fear, or desperation – have consequences. What happens as a result can affect not only the person who made a choice, but also the lives of other people. It’s a important piece of wisdom that some people do not learn until after they have destroyed something or someone they love.