With two of the Mortal Instruments now in Valentine's hands, the world of the Shadowhunters teeters on the brink of civil war. Jace and the Lightwoods are recalled to Idris, the Shadowhunters' remote and hidden home country, where a search has begun for the last of the Instruments, the Mortal Glass.

Sixteen-year-old Clary Fray is an ordinary teenager, who likes hanging out with her friends. But everything changes the night she witnesses a murder, committed by a group of teens armed with medieval weaponry. The murderous group are Shadowhunters, secret warriors dedicated to driving demons out of this dimension and back into their own.

With her mother in a coma and her father hell-bent on destroying the world, Clary is dragged deeper into New York's terrifying underworld of werewolves, demons and the mysterious Shadowhunters. Discovering the truth about her past was only the beginning, now Clary must save the world from her own father - the rogue Shadowhunter Valentine.