'Mortal Instruments': Director Takes Us Inside 'Moody' Trailer Music

'They're so eager to see something that we figured it's time to get something out to them,' Harald Zwart tells MTV News.

The world was welcomed into the "City of Bones" on Wednesday (November 14) when MTV News debuted the exclusive trailer for the big-screen adaptation of Cassandra Clare's best-selling novel.

Starring Lily Collins and Jamie Campbell Bower, "The Mortal Instruments: City of Bones" follows teen Clary Fray, who with the help of dreamy demon-destroyer Jace Wayland, searches to uncover the truth about her family's history in the mysterious Shadowhunter society.

With principle photography wrapping in Toronto just last week, many fans were surprised to get their first look at the film so soon, so when director Harald Zwart stopped by MTV News this week, we had to ask how he managed such a tight turnaround.

"Well, we start almost on the trailer as soon as we can," he explained. "After a couple of weeks [into production], we have enough material to put something together. Normally, we do that just to get people excited about the movie, and then as we shoot, we drop [scenes] into the trailer. The trailer doesn't have all the really cool shots, but it will eventually."

Zwart largely credited fans with inspiring the quick cut -- which though labeled as a teaser, clocks in at nearly two minutes.

"Sometimes I think you can rush these things, but we were really eager to get it out to the fans," he said. "There's a huge fan base. Every day when we were filming, there were fans outside of our set every day waiting. They're so eager to see something that we figured it's time to get something out to them."

And what they got was a grand, epic-feeling preview of Clare's world of dark forces and the Shadowhunters tasked with defeating them. And it could be said much of that epic feeling was achieved with the sweeping back track "Kaneda's Death, Pt. 1" by John Murphy.

"Well, that song is very moody, and it's a very right tone for the movie," Zwart said. "'Cause like you said, it is a very epic movie, yet it's kind of an intimate drama. It still touches on big subjects, and I just think it lends itself perfectly to the trailer. It gives that slightly mysterious yet serious tone."

"The Mortal Instruments: City of Bones," co-starring Jared Harris, Lena Headey and Jonathan Rhys Meyers, hits theaters August 23, 2013.

Check out everything we've got on "The Mortal Instruments: City of Bones."