The Mortal Instruments is a series of young adult novels by American author Cassandra Clare and is the first of the Shadowhunter Chronicles. The series follows Clary Fray, Jace Herondale, Simon Lewis, Isabelle Lightwood, Alec Lightwood and other Downworlders and Shadowhunters in the New York Institute. Seemingly normal at first, Clary soon gets sucked into the world of Nephilim and other creatures when she finds out that she is a Shadowhunter.