Six minutes of a highly anticipated summer blockbuster played before IMAX screenings of 2007’s “I am Legend.”

The six minutes showed thugs in clown masks robbing a mob-owned bank. As soon as one thug serves his role in the heist, another thug guns him down, and so on. Only one of the masked men survives.

“Criminals in this city used to believe in things. What do you believe in, huh? What do you believe?” the wounded bank’s manager yells as he lies on the floor. Before he kills him, the remaining hood reveals to the manager the mutilated clown-like grimace underneath the mask and says, “I believe that whatever doesn’t kill you makes you … stranger.”

This is how moviegoers will meet the late Heath Ledger’s interpretation of The Joker on July 18 when “The Dark Knight” premieres in movie theaters. The Batman will not chase the criminal through a manufacturing plant, causing him to fall into a vat of toxic chemicals. Tim Burton told that story in 1989.

What moviegoers may not have noticed while watching six minutes of the two-and-a-half-hour movie is that The Joker’s thugs talk to one another about their boss as though they never met him. In the end, the masked men kill one another on his orders, leaving him with the stolen money, which is more or less what happens in the 48-year-old “Detective Comics #45: The Case of the Laughing Death.”

In the comic book, The Joker dresses up as an ordinary music store owner and orders goons to commit robberies. But he beats them to each robbery in his normal clown-like guise, so they only serve to distract The Batman. His thugs ultimately go home empty-handed.

Director Christopher Nolan said in past interviews that the critical influence for the film was The Joker’s first two appearances in comics and “Batman: The Long Halloween.”

“Batman #1: Batman vs. Joker,” which DC Comics published in 1940, shows that The Joker character publicly threatens people who he wants to rob or with whom he holds a grudge, leaving the bodies of his victims with chemically induced smiling faces.

What is notable about the comic book is that he goes through extraordinary lengths to follow through on his death threats, including successfully impersonating a police officer to get to one of his targets. This is impressive because The Joker has noticeably bleached white skin.

“Batman #2: The Case of The Joker’s Crime Circus,” which DC Comics published in 1941, also shows he has a penchant for dressing up in costumes to get access to the home of people he plans to rob.

“The Dark Knight” trailers show that Gotham mobsters have turned to The Joker for help to regain control of the city. He likely killed or robbed them blind to command their obedience or garner their attention.

They are also under attack by a new, maverick district attorney, Harvey Dent (Aaron Eckhart), who with help of The Batman and Lt. James Gordon, is working to put on trial mobster Salvatore Maroni (Eric Roberts), Gotham’s new crime honcho in the movie.

The mobsters showed desperation during Dent’s successful run for Gotham D.A., sending voters e-mails alleging he has an extensive arrest record, paying to broadcast TV ads alleging that he intimidated a police officer to falsely accuse other cops of corruption, and they burned down two campaign offices, the Gotham Cable News Web site reported.

The Web site is a part of Warner Bros. Pictures’ online campaign to market the movie.

“Batman: The Long Halloween,” which was published by DC Comics in the late ’90s, shows that mob kingpin Carmine Falcone tries to launder his family’s money through the Gotham City Bank. But Bruce Wayne, who is a member of the bank’s board of directors, intercedes under the guise of The Batman to prevent this from happening.

He goes further. With the help of Dent, The Batman later finds the cash in a warehouse and burns it to ashes.

What is notable about the comic book series is that it shows Dent’s antipathy toward criminals. Dent not only suggests how he would kill a certain gangster, he is content when he hears someone else did the job.

This may play out in the movie.

As part of the storyline for the 13-issue comic book series, Dent puts Maroni on trial. When he takes the stand to answer questions, the mobster throws acid toward the left side of Dent’s face, horribly scarring him.

A snippet from a movie trailer implies that The Joker scars Dent’s face, igniting spilled liquid on which the ill-starred D.A. lies.

No matter how it occurs, Warner Bros. Pictures footage and Aaron Eckhart in past interviews confirm that Dent will transform into the criminal Two-Face in the movie.

As Two-Face, he kills Maroni in “Batman: The Long Halloween,” and he likely kills him in “The Dark Knight” as well.

Eckhart alluded to this during an interview at a June 29 press junket.

“If you notice who Harvey Two-Face disposes of, it is not random. It still has a sense of justice to it,” Eckhart said at the junket. “I think he cannot get away from his true nature.”

Bill Ramey, who runs the Batman on Film Web site and was invited to a press screening to the movie, confirms that The Scarecrow (Cillian Murphy), who used fear toxin against the citizens of Gotham in the terrorist attack against the city in 2005’s “Batman Begins,” appears at the beginning of the movie.

News anchor Mike Engel (Anthony Michael Hall) recently reported on the GCN Web site that a 17-year-old Gotham resident died when at a night club he experimented with Ecstasy that was laced with Crane’s toxin. Later in the broadcast, a Gotham Times reporter told Engel about reported sightings of a man wearing a burlap sack leading “disturbed” people throughout the city.

Could they be the criminals who escaped from Arkham Asylum?

Ramey said online scuttlebut about actress Sarah Dunn’s role in the movie is false. Harley Quinn, The Joker’s moll, does not appear in the movie.

Most trailers for “The Dark Knight” indicate it will be an action-packed flick, though a scene in which The Batman talks to The Joker in what seems to be an interrogation room at the Gotham City Police Department looks just as promising.

“Does it depress you, how alone you really are? You had plans. Look where that got ya,'” the Joker says.

He appears determined to prove they are similar by pushing The Batman to kill him, to break his one rule. This plays into The Joker’s theory in “Batman: The Killing Joke,” a graphic novel which DC Comics published in 1988, that it only takes one day of great misfortune to turn a sane man into a psychopath.

Christian Bale said at the June 29 press junket that “there is a very fine line of what is the quickest way to solve a problem, much as with Batman questioning his own rule. What is the quickest way to finish The Joker and assure that no one else dies? Well, that is to kill him.”

“However, he is lowering himself by doing so,” Bale said at the junket.

At the same time, Bruce Wayne, the man underneath the mask, considers giving up his mission to rid the city of crime, as citizens have overwhelmingly embraced Dent as their protector.

What he will decide is obvious to comic book fans, but the events that will shape his decisions should prove to be riveting for everyone.