Lena Headey (300, "Game of Thrones"), Jared Harris ("Mad Men," Sherlock Holmes: A Game of Shadows) and Godfrey Gao (All About Women) have joined the cast of The Mortal Instruments: City of Bones, which has also added that subtitle to its official production name.

Headey will play Jocelyn Fray, Harris will play Hodge Starkweather, and Gao is set to portray Magnus Bane. They join the previously-announced Lily Collins as Clary Fray, Jamie Campbell Bower as Jace Wayland, Robert Sheehan as Simon Lewis, Jemima West as Isabelle Lightwood, Kevin Durand as Emil Pangborn and Robert Maillet as Samuel Blackwell.

"The Mortal Instruments" is a series of six young adult fantasy books written by Cassandra Clare and published by Simon & Schuster/Margaret K. McElderry Books. In the series’ first book, the #1 New York Times bestseller "City of Bones," set in contemporary New York City, a seemingly ordinary teenager, Clary Fray, discovers she is the descendant of a line of Shadowhunters, a secret cadre of young half-angel warriors locked in an ancient battle to protect our world from demons. After the disappearance of her mother, Clary must join forces with a group of Shadowhunters, who introduce her to a dangerous alternate New York called Downworld, filled with demons, warlocks, vampires, werewolves and other deadly creatures.

The Mortal Instruments: City of Bones is targeting an August 23, 2013 release.