This Friday, a new trailer for The Dark Knight Rises will be attached to The Avengers, but it turns out the trailer is being released early, one frame a time.

Warner Bros. has created an interesting new campaign in combining the release of a highly anticipated new trailer with building awareness and buzz around their film in what amounts to a worldwide treasure hunt.

Fans who go to the official web site for The Dark Knight Rises will see the Gotham Police Department file on the Batman investigation. Inside are lots of cool items, but the most important piece of info reveals Batman-related graffiti popping up all over the world. Citizens who locate, photograph and upload the graffiti to Twitter with the hashtag #tdkr07202012 will unlock one new frame from the trailer.

The concept behind the viral campaign is that Gotham City police are increasing their efforts to locate Batman and/or anyone supporting him or advocating his return as Harvey Dent Day approaches.

The upcoming film is set eight years after the conclusion of The Dark Knight and Batman has mostly disappeared from Gotham. He's wanted for the murder of Harvey Dent, two police officer and two other people. What's not known is precisely who all the dead people are (besides Dent). Their identities have been the subject of discussion and debate among Bat-fans.

Will you try to find the Batman graffiti in your city?

(Click on the image for a larger version)