City of Fallen Angels by Cassandra Clare

City of Fallen Angels is the fourth book in the Mortal Instruments series by Cassandra Clare. The series was meant to end with City of Glass; however, it was announced in March 2010 that a fourth book would be added, with Cassandra Clare later saying how she views this as a "second trilogy" in the series. The book was released on April 5, 2011. - Wikipedia