Robert Maillet and Kevin Durand are joining the cast of "The Mortal Instruments," an adaption of Cassandra Clare's bestselling book series.

Screen Gems is spearheading the urban fantasy series, starting with the first book "City of Bones." Constantin Film and Unique Features are teaming with the studio for the project. It will lens in Toronto Aug. 15 for an Aug. 23, 2013 release.

"City of Bones" centers on 15-year-old Clary Fray (Lily Collins), a seemingly ordinary girl who discovers she is the descendant of a warrior clan called Shadowhunters, who combat demons around the world.

Harald Zwart ("The Karate Kid") is directing from a script by Jessica Postigo and I. Marlene King. Martin Moszkowicz and Dylan Sellers will executive produce, with Robert Kulzer, Michael Lynne and Robert Shaye in producer roles.

Along with Durand ("I Am Number Four," "Real Steel") and Maillet ("Sherlock Holmes," "Immortals"), "The Mortal Instruments" also stars Jemima West and Jaime Campbell Bower as Jace Wayland.

"City of Bones" ranked No. 8 in children's books on the New York Times Best Seller list in 2007.

Should the book's adaption enjoy box office success, audiences can expect to see big screen treatments for the series' other installments, which include "City of Ashes," "City of Glass," "City of Fallen Angels" and "City of Lost Souls."

The next book in the series, "City of Heavenly Fire," is expected to conclude the storyline.