Odd ideas tend to float through the room, when writers pitch proposals for TV shows.

Still, this one was odder than most: Michael Green wanted a modern re-telling of David, the shepherd lad who beat Goliath and became king.

"There were some cocked brows," Green recalled. "(People thought,) 'You want to do what?'"

Still, NBC said yes. "Kings" debuts Sunday as an epic and expensive tale.

When Green pitched the idea he was working on "Heroes" -- big and bizarre and successful. "We'd just done a scene where a guy came back from the future to tell someone to save the cheerleader," he said.

Compared to that, the David story is simply your standard adventure. "David is one of the most classic heroes of all time," director Francis Lawrence said. "And one of the most complicated."

He sparks an epic story, said Ian McShane, who co-stars as King Silas Benjamin. "Take Shakespeare (or) the Greek Tragedies, they're all soap operas on a different level. I mean, they deal with tragedy, love, betrayal, lust, grandeur."

In this case, we have Gilboa, centered in a city that looks like New York but isn't. It has a dangerous neighbor (Gath) and a strong king who claims divine influence.

"I'd see Silas as somebody who was rebellious in the ranks," McShane said. "(He) rose through personal lunacy or heroism -- they're quite closely aligned, those two -- and became a leader."

Now he's worried about the next generation, McShane said. "My son (is) not all that I think a son should be. I have a daughter who (had) a sickly childhood and developed into this beautiful young woman."

Then a soldier named David Shepherd takes strong action. He destroys a tank named Goliath and rescues several prisoners; one turns out to be the king's son.

David is whisked to the capital. A handsome, rural guy, he is declared a hero. Still, Green warns, "no one stays good forever."

This was a tough role to cast, Green said. "We spent a lot of time looking at a lot of people, trying to find someone who was appealing and who felt like he was at the beginning of a journey but also had the acting chops."

He chose Christopher Egan, 24, who had some success in his native Australia. He's new to the U.S., except for NBC's "Vanished" series, a few guest roles, and playing Roran in the movie "Eragon."

Egan is part of an international cast. McShane ("Deadwood") is British; so is Eamonn Walker, who plays the Rev. Ephram Samuels, a skeptical advisor. Sebastian Stan, who plays the prince, was born in Romania and grew up there and in Austria; he's best known as Carter on "Gossip Girl."

Others are Americans -- Susanna Thompson as Queen Rose, Dylan Baker as her rich brother, Macaulay Culkin as his son, Allison Miller as the princess.

Some will seem a little familiar; so will Gilboa itself. The show is filmed in New York, with digital trickery inserting fictional parts.

Still, Green feels the special effects aren't what matters. "It's less about digital technology and more about how the audience has evolved to want ... more sophisticated storytelling."

That's a fresh trend, he feels. "Every new show that's really ambitious is built on the backs of the ones before it. I don't think 'Heroes' could have happened without 'Lost' and I don't think we could have happened without 'Heroes' and 'Alias' before it."

Those shows set the stage for Green to pitch a big, bizarre idea about David the Shepherd, Goliath the tank and the kingdom of Gilboa.