And one of the reasons is because lead Jason Ritter doesn't even know what "The Event" is.

"I've been in the dark," he joked, saying the producers haven't told him the earth-shattering occurrence.  "I'm pretty terrible at keeping secrets, so it's actually a relief not to know what the event is."

"It's all about ramping up to the event," said co-star Blair Underwood, and says that the consequences and aftermath play a big role.  "It's something that can potentially change the course of mankind as we know it."

"The Event," which begins airing next week on NBC, follows a video game developer (Ritter) who, while searching for his suddenly-disappeared girlfriend, stumbles upon the biggest cover-up in U.S. history.  We chatted with Ritter and Underwood Wednesday morning about the upcoming premiere, and the guys promised an action-packed mystery-thriller that's "95 percent political intrigue, 5 percent sci-fi."  Underwood mentioned the multi-faceted nature of the show, which combines a love story, government conspiracies and suspense.  

Underwood plays America's first Afro-Cuban president, with Lisa Vidal starring as the Puerto Rican first lady.  He said that this genre's intricate plots can sometimes be confusing and can "leave the audience frustrated."  He said the show's producers and writers work hard to keep viewers up-to-speed and entertained. 

To that token, we asked how "The Event" differentiates itself from similar programs, like "Lost," "24," "Heroes," "V" and last season's ill-fated "FlashForward."

Ritter pointed to the "The Event's" extensive mythology: "Our creator, Nick Waters, had been brewing this story for four full years.  He was writing for other shows and made this as a 'fantasy pilot.'  It's aged like a wine in our creator's mind."

"It has elements of '24' in its tone," Underwood added.  "Those shows are gone now and this show fills the void."  

But he clarified that "It's not just tapping into those touchstones and those elements -- it's a really well-done show... We were able to take what worked and what didn't work for this genre."  He also said that part of the creative team of "24" signed onto this project, as well.

"It generally takes place in the world we're living in, with just a little fantastical element," Ritter said.  

Underwood added that "a lot of it will resonate in real life," and the plot references topics like immigration and reinventing the traditional image of America's first family.

They also emphasized the "mind-blowing and exciting" action sequences, as well as the pervasive government conspiracy.

"My father was in intelligence at one point; [served] 27 years in the military," Underwood explained.  "I believe the government knows about things we don't know about -- or don't need to know about," and said that notion was a big part of the show's appeal.  "The audience is much more educated and sophisticated nowadays.  We want shows that are smart.  People want to use their minds and think."

Ritter said his self-performed stunts have marked his experiences on the set.

"I've never had to be this physically after before," he said, noting one exception of pretending to jump off a cliff.

"Some things you want to leave for the professional," he laughed.  "It was pretty scary filming it.  We were all tied in and very secure, but I had to run right up to the edge.  It was a little terrifying."  He said his character's missing girlfriend is "motivating him past his fear."

Catch the series premiere of "The Event" Monday, September 20 at 9 p.m. EST on NBC.