Credit: Pararmount Pictures

Marvel Studios president and "The Avengers" producer Kevin Feige told "Nightline" his next project, "Iron Man 3," will be "very different" and just because it's a sequel doesn't mean the audience will know what's coming.

"It's going to be very different, very unique and I think not ascribe to any specific formula that they think they may have pegged us on," Feige told ABC's Chris Connelly. "It's all in the story. It's where you take Tony Stark on his journey in an unexpected way and have him come out of the Avengers a slightly changed individual, which people will see when they see the movie."

Filming for "Iron Man 3? will begin in the next few weeks, he said.

The first "Iron Man," which launched the Marvel Comic movie franchise, and "The Avengers," which brings four Marvel superheroes together to save the world, are what Feige called the "bookends" of the "Marvel cinematic universe."

The franchise produced "Iron Man 2," "Captain America," "Thor" and "The Incredible Hulk" ahead of "The Avengers," which is produced by ABC News' parent company, The Walt Disney Company, and premieres in theaters nationwide on May 4. But Feige said he believes in making each comic book character film different and said he is constantly working to find new ways to surprise the audience.

"I believe each movie, whether it's a new character movie or the sequel to an existing character movie, needs to have its own set, its own formula, its own rules," he said.

Watch the full interview with "The Avengers" cast on "Nightline" TONIGHT at 11:35 p.m. ET

Credit: Eric McCandless/ABC