Jason Momoa and Amber Heard Tease 'Introduction' to Aquaman: 'We're in the Origin Story' (Exclusive)

ET spoke with the 'Aquaman' cast backstage at CinemaCon to get scoop on Nicole Kidman's Queen Atlanna and the movie's villains.

"We've never seen Aquaman in the world," Amber Heard told ET ahead of Tuesday's Warner Bros. presentation at CinemaCon. "This is our real introduction to this new version of it. And what better way to do it?"

Though both Jason Momoa's Arthur Curry (aka Aquaman) and Heard's Mera were seen in last year's Justice League, the upcoming Aquaman solo movie, out Dec. 11, will fill in his backstory. "I think after Justice League, everyone got a pretty refreshing look at what Zack [Snyder] intended for Aquaman," the actor explained. "He's a little grump and gruffy."

"Now, we get to know why he's that way," Momoa continued. "We're in the origin story, and we're going to find out why he wasn't loved in Atlantis and why he wasn't loved on the surface. Now he has something that's beautiful that can help the world...And it's someone bringing it out of you even though you don't think you have it."

Director James Wan enlisted Nicole Kidman (in her first comic book movie since 1995's Batman Forever) to play Queen Atlanna. "My mom is Connie Momoa, but my mom in this movie is Nicole Kidman," Momoa said with a laugh. "Not quite as great as my mom, but it was hands down one of the greatest actresses I've ever worked with...That's why she's an Oscar winner."

"She's one of the most beautiful on the inside, soulful, incredibly kind-hearted women," Heard added. "She is truly a powerhouse and I was honored to work with her. I was nervous working with her, of course! She's one of the greats."

Rounding out the cast are Yahya Abdul-Mateen II as Black Manta ("He's a pest, that's how I like to describe him") and Patrick Wilson as Orm, aka Aquaman's half-brother and the villain Ocean Master.

"[Aquaman] comes into my world, where I've lived and grown up, so there's a brutality that he comes in and a finesse that Orm possesses," Wilson teased. "They make for interesting fights, because obviously he's a big boy -- no matter how much weight I put on or work out. We just have different skill sets."

What you won't see much of in Aquaman, it turns out, is water. "It's all CG," Momoa revealed, while Wilson explained, "The conceit is we are flying around in water and we're talking underwater, so clearly we can't do that. So, it was a ton of wire work. You know when the stunt guys are going, 'Wow, I've never done this much wire work before.'"

"I just have severe bruising right here from harnesses," Momoa joked, motioning to his inner thighs. "Don't pan down. It's just swollen, that's why its weird."