The Event is being described as the next Lost, The 4400 or Flash Forward.
Like these twisty dramas, it revolves around a complex mystery that keeps everyone guessing - including its actors.
Ritter plays Sean Walker, a regular guy who, in the first episode, loses everything - his girlfriend, his electronic details and his passport.
His search for his would-be fiancee, Leila Buchanan (Sarah Roemer), leads him to unwittingly expose the biggest cover-up in American history, and into the path of newly elected American President Martinez (Blair Underwood), Sophia, the mysterious leader of a group of detainees (Laura Innes of ER), and Sean's shadowy father-in-law (Scott Patterson.) All we know from the pilot episode is that what happens next leads him to wield a gun on a plane.
And in another scene, a plane is making a beeline for the president.
Sean's storyline - which at first is told in a series of flashbacks - is one of Ritter's worst nightmares: "It's the idea that everything you counted on as being a truth is taken from you.
"That your girlfriend will be in your room when you get back because that's where she said she would be, and you'll get married and your information won't be erased.
"To have the entire system turn on you is a pretty terrifying thing."
Ritter says that like his character, he has also been left in the dark throughout the series, which helped him convey Sean's panic, confusion and paranoia.
"I enjoy not knowing where it's going and just trying to figure it out as I go along.
"Sean's trying to get clues from every person he interacts with.
"So for me, as an actor, I don't know if they are going to be there just for the day, or be a regular on the show.
"I am trying to glean clues from their character's behaviour as much as Sean is.
"I've begun to not trust anybody either."
Ritter is finding the uncertainty of shooting television episodes as opposed to acting in a film or theatre production exciting - you can't read ahead to find out where your character will end up.
"It actually kind of mirrors life in a way because you don't know what's going to happen.
"You can guess, but you can always be totally blindsided."
The Event is little-known writer Nick Wauter's dream project.
The idea came to him as the show he would write if he was given a whole lot of money, Ritter says.
As it happened, his timing was spot-on; he pitched it to producers just as NBC was looking for something to be the next Lost or Heroes.
"Basically, they said to the producer they were looking for some big event-type show, to which he said, `Oh well, I might have just the thing for you'."
Pilot season rolled around and Ritter needed only to glance at the script to know he desperately wanted a part in the series.
After working mainly in independent films, Ritter decided to be slightly more selective about what he auditioned.
But The Event and, more specifically, Sean's character, fascinated him, and he immediately wanted to be part of it.
Ritter was a huge fan of Lost, but he was more intrigued by the writing of The Event than any parallels people have drawn between the two shows.
Ritter has even found himself pulling out his inner action hero while filming.
He says he will perform his own stunts wherever he is allowed - and there have been shoot-outs and glass-shattering explosions, as well as a scene of him driving away from a big explosion.
Only the really death-defying stunts are left to the professionals.
"That was totally terrifying.
"Before we got there I was like, well, how hard can it be, I'll give it a shot.
"I didn't see that it slanted out into the ocean and there was a good chance that if you didn't run fast enough you could miss clearing the rocks."
After a successful opening, NBC ordered another 14 episodes of The Event to complete a full season.
LOWDOWN
Who: Jason Ritter.
What: Plays the lead in new series The Event.
When and where: Tuesday, 8.30pm on TV3.
Known for: Playing Mark in Parenthood, and being the son of the late John Ritter (Three's Company and Three's A Crowd).
- The Event screens on Tuesdays at 8.30pm on 3.
