On their birthday, Marissa and Clary Fray discovers a surprise concerning their life. The teenagers are not who they think are -- They comes from a long line of human-angel hybrids, called Shadowhunters, who hunt demons. After their mother is kidnapped, The twins is thrust into the world of demon-hunting. Clary relies on mysterious Jace and Mary relies on his fellow hunters Isabelle and Alec to help them navigate the dark world. While living in this new world among creatures like vampires and werewolves, The Twins's best friend Simon helps them uncover answers that could help them find their mother. The fantasy show is based on a series of young adult books by Cassandra Clare.