By Piya Sinha-Roy

LOS ANGELES (Reuters) - Director Quentin Tarantino unlocked the secrets of his upcoming action flick "Django Unchained" at Comic-Con on Saturday with explosive clips of the slave revenge movie, which takes place in the pre-Civil War U.S. South.

The director entered the pop culture convention's main hall in his trademark quirky sunglasses and a fedora, and was given a raucous welcome by some 7,000 audience members, some of who waited overnight to hear him speak.

"Django Unchained," due in theaters this coming December, is the latest from the maker of "Kill Bill" and "Pulp Fiction," who was joined in a panel by actors Jamie Foxx, Christoph Waltz, Kerry Washington, Don Johnson and Walter Groggins.

Until Saturday, little was known about the film and no footage had been seen in public. Tarantino said he still had one last week of shooting. He revealed that Jonah Hill is playing a racist and confirmed Sacha Baron Cohen will not be appearing.

The story follows Django (Foxx), a black slave freed by a rebel dentist-turned-bounty hunter, Dr. King Schultz (Waltz). The pair embark on a bloody bounty hunting expedition to rescue Django's captured slave wife, Broomhilda (Washington).

Fans were treated to an eight-minute promotional film reel showing scenes of Foxx and Waltz taking down villains, including Johnson and Leonardo DiCaprio. The gritty footage featured the director's trademark violence fused with sharp humor and Western music.

"One of the fun things was to take the Western genre that we know so well and place it in the Antebellum South and put a black character in the middle of it. Do the Western clichés, but do them in the South," said Tarantino.

In a twist from his villainous part in Tarantino's "Inglorious Basterds," Waltz plays a complex good guy opposite Hollywood hero DiCaprio, who plays evil plantation owner Calvin Candie. Waltz told reporters prior to the panel that Tarantino had written the role with DiCaprio in mind.

In the convention hall, Foxx talked about his experiences with racism when he grew up in Texas and explained how he used his past to tap Django's emotions.

Washington is the latest actress to join Tarantino's roster of talent in strong female roles, including Uma Thurman and Diane Kruger. But she puts a royal black twist on her Broomhilda character. "She is the princess who is rescued from the tower and particularly for a black woman, that's not really an experience that we've had historically," said Washington, who learned to speak German for the role.

From the look at the film clips, Tarantino adds a touch of love, too, as the human tale of a man attempting to recapture his woman is a central thread in the story.

"So much of the institution of slavery was about breaking up families and not making it possible to have healthy marriages, so the idea that in this world of slavery, that love could conquer this evil institution and that a man could rescue his wife outside the chains of slavery, I thought that was so beautiful and important," Washington said.

(Reporting By Piya Sinha-Roy; editing by Bob Tourtellotte and Todd Eastham)