'The Mortal Instruments: City of Bones' Trailer Introduces Lily Collins, Demon Hunter (Video)

The adaptation of Cassandra Clare's YA novel follows a band of half-angel teens who must protect the world from demons.

As one young-adult book-to-movie franchise takes its final bow, another is preparing to make its first appearance.

With the Twilight series’ final film hitting theaters Thursday night, it’s time to trade in those good-looking vampires for half-angel teen demon killers.

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The first trailer for The Mortal Instruments: City of Bones has premiered, introducing viewers to Clary Fray (Lily Collins), a young woman who realizes she can see things that others can’t. She then discovers she is the descendant of a secret cadre of half-angel warriors called Shadowhunters. She’s tasked with joining the band of fighters as they try to protect the world from demons.

The film, an adaptation of Cassandra Clare’s YA fantasy novel, also stars Jonathan Rhys Meyers, Jamie Campbell Bower and Mad Men’s Jared Harris.

The first trailer features Clary seeing Jace (Bower), who helps her discover who she really is. There are plenty of shots of creepy looking demons and magical realms, and it looks like it all leads to an epic battle where the Shadowhunters are vastly outnumbered but ready for the fight.

Directed by Harald Zwart, the film hits theaters Aug. 23.