The long-gestating adaptation of The Mortal Instruments is finally moving forward, and now two antagonists have been cast.  Based on the first book in Cassandra Clare‘s young adult novel series, The Mortal Instruments: City of Bones, the film centers on a young woman who discovers she is the descendant of a line of secret cadre of half-angel warriors locked in an ancient battle to protect the world from demons.”  Lily Collins and Jaime Campbell Bower are set as the leads, and Variety now reports that Kevin Durand (X-Men Origins: Wolverine) and Robert Maillet (Sherlock Holmes) have been cast as Pangborn and Blackwell, two henchman of the film’s main villain, Valentine.

The film adapatation had been in limbo when was without financing, but Screen Gems and Constantin Film recently teamed up to back the pic.  Harold Zwart (The Karate Kid) will direct, with The Mortal Instruments set for release on August 23rd, 2013.  Hit the jump to read the official synopsis.

Here’s the synopsis for The Mortal Instruments:

CLARY FRAY (Lily Collins) is an ordinary Brooklyn teenager until the night she meets the mysteriously tattooed JACE, who turns out to be a half-angel warrior known as a Shadowhunter. When Clary finds out her mother JOCELYN has been abducted, she desperately hopes Jace will be able to help. After a whirling golden portal transports her across time and space in a heartbeat, Clary realizes she too has the powers of the Shadowhunters. But can she harness them in time to save her mother?

Clary, Jace and their fellow Shadowhunters endure one breathtaking battle after another against vampire, warlocks and demons—only to discover Jocelyn hid a terrible secret from the fiercest warrior of all: VALENTINE. Cast out from the world of Shadowhunters, Valentine abducted Jocelyn believing she had a powerful tool known as the Mortal Cup. Using her newfound gifts, Clary finds the Cup, only to be brutally betrayed and forced to relinquish it.

Still reeling from this setback and racing to save Jocelyn before it’s too late, Clary finds herself caught in a battle between forces she barely understands. Based on the best-selling series by Cassandra Clare, MORTAL INSTRUMENTS is a magnificent urban fantasy rich in detail and suspense, about a girl’s journey to the darkest corners of the underworld to save those she loves.