There lives a world, unlike our own, where the things of nightmares and legends are of flesh and blood, and who seek to destroy us, and who probably would, if not the fabled warriors of Angels fought day in and day night to protect the mortal realm from the attack of those that are villainous and inhumane - Demons. These angelic creatures are called Nephilim in our world, though are more commonly referred to as Shadowhunters in the Shadow World. They are the protectors of Earth and the Shadow World, and are the only neutral sources in the land.

However, the once pure lines will be broken when a child is taken in by a man who is not what he appears. Will this bond be the end of both worlds as we know it, or the salvation of several species at a time?