Screen Gems, Constantin Film and Unique Features have joined forces to bring author Cassandra Clare‘s New York Times best-selling book series The Mortal Instruments to the big-screen. The script was written by Jessica Postigo, and is based on the first book in the series entitled, City of Bones.

City of Bones begins with a sixteen-year old girl named Clary Fray, who lives in New York with her mother, an artist. She comes home one night to find her apartment ransacked, her mother gone — and a slavering demon ready to tear off her head. Once the demon’s dealt with, Clary follows the clues to her mother’s disappearance into an alternate New York filled with hideous demons, hard-partying warlocks, not-what-they-seem vampires, an army of werewolves and the scariest thing of all: the secrets of her mother’s past. She also finds herself torn between two boys — her best friend Simon, for whom she’s developing new feelings, and the mysterious demon hunter Jace, who has a past more tangled than her own. She becomes a part of the secret word of the demon hunters, or Nephilim, and as she does discovers she might be more connected to them than she originally thought.

The Mortal Instruments series includes City of Bones, City of Ashes, City of Glass, and the upcoming City of Fallen Angels. The novels are published by Margaret K. McElderry Books, a division of Simon & Schuster, Inc.

The Mortal Instruments is slated to hit theaters in 2012.