Stephanie Sanditz has been hired to write 'The Mortal Instruments' prequel 'The Infernal Devices'.

Constantin Films is beginning development on a prequel to its forthcoming fantasy film - which stars Lily Collins, Jamie Campbell Bower and Robert Sheehan - in anticipation of the success of 'The Mortal Instruments: City of Bones', according to The Hollywood Reporter.

Constantin Films has hired Sanditz to pen the screenplay for the first book in the trilogy, which serves as a prequel to 'The Mortal Instruments', and are also looking for a director to helm the movie.

'The Mortal Instruments' centres on a young girl, Clary Fray (Collins), who, upon her mother's kidnapping, discovers she is part of a magical species of angels known as Shadowhunters and finds herself immersed in a fantasy world of angels, vampires, witches and warlocks.

The prequel series, meanwhile, is set in the Victorian era and features the ancestors of the main book series' protagonists.

Both book series were written by young adult author Cassandra Clare and are said to be similar in tone to hit book-to-movie franchises 'Twilight' and 'The Hunger Games'.

The first big screen adaptation of Clare's fantasy book series, 'City of Bones', is due for release in August.