The Mortal Instruments Book 1 - City of Bones (A Shadowhunters Novel).
Welcome to the Shadow World, where Nephelim live, and you meet Clary Fray, Jace Wayland, Alec and Izzy Lightwood, and of course, the enigmatic Magnus Bane as they try to resolve so much drama in New York while trying to figure out what's up with Clary.