About
The Mortal Instruments is a series of six young adult fantasy novels written by American author Cassandra Clare, the last of which was published on May 27, 2014. The Mortal Instruments is chronologically the third series of a planned six in The Shadowhunter Chronicles but was the first one published.
 
Summary 
The Nephilim race was created a millennium ago when the angel Raziel blended his blood with human blood. Our invisible guardians are the human-angel hybrids who live among us, unseen but always present. They identify as Shadowhunters. The angel gave the Shadowhunters the Grey Book, which contains the laws they must follow. Their mission is to defend our planet against interdimensional parasites known as demons, who travel between worlds razing and destroying everything in their path. Along with maintaining peace among the warring Downworlders—the human-demon hybrids known as warlocks, vampires, werewolves, and faeries—is another duty assigned to them. The enigmatic Silent Brothers support them in their responsibilities. The archived records of every Shadowhunter ever born are held by the Silent Brothers. Additionally, they keep guard over the three divine artifacts that Raziel's children received from the Angel, the Mortal Instruments. A sword is one. A mirror is one of them. Finally, there is a cup. The Nephilim have guarded the Mortal Instruments for a millennium. That was, however, prior to the Uprising, the civil war that all but destroyed the Shadowhunters' underground society. The war never fully healed, even though Valentine Morgenstern, the Shadowhunter who began it, is long dead. It has been fifteen years since the Uprising. Clary Fray barely anticipates seeing a murder when she goes to the Pandemonium Club in New York City, much less one carried out by three teenagers wielding odd weapons and covered in strange tattoos. The body then vanishes into thin air. When the killers are undetectable to others and there is no visible evidence of the boy's death—not even a smear of blood—it can be difficult to report the crime to the police. Was he a boy, instead? Clary is meeting the Shadowhunters for the first time; they are warriors whose mission is to purge the planet of demons.