It takes a rich broth to draw people into a "Lost" season.

For the hard-core buff, there are hints of fantasy, plus the overall mythology of this island-survivor tale. For others, there's action and romance.

And as the new season starts Jan. 21, there's a bonus: Sawyer (Josh Holloway) spends the entire first hour with his shirt off.

"For some mythology fans, the story is enough," said producer Damon Lindelof. "For the others — Sawyer doesn't have his shirt on."

That has something to do with a sudden shift in time. He was bare-chested when it happened; now his shirt seems to be in another time.

"Some female fans might not like time travel," producer Carleton Cuse said. "But they won't mind, if it's the reason Sawyer doesn't have a shirt."

They're joking about that (a little), but "Lost" does assemble diverse elements. It's had flashbacks, flash-forwards and stories set on several continents.

"What makes it especially difficult is the speed with which we do it," Lindelof said. "Every nine days, we're (making) a new hour."

For a while, viewers couldn't even agree on whether this is a fantasy story.

"It was always an adventure show," Cuse said, "but it's a little like the Indiana Jones movies. You go along with an adventure the whole time and in the end, someone's face melts."

In the early years, viewers could concoct semi-logical explanations for most odd events. Then "Lost" offered stronger hints of fantasy.

As last season ended, Ben Linus (Michael Emerson) somehow "moved" the island. As this season starts, the island keeps bouncing in time.

"The big question is, 'Where did it go?' " Cuse said. "Or, 'When did it go?' "

The island might be in earlier times: The camp (and the shirt) are gone; the hatch hasn't blown up yet. In a separate story, the people who escaped to the Mainland are told they must return — if they can find the island.

Not all of this was planned when the show started, Lindelof said. "When you make a pilot film, you don't know if a show will last years or just two hours."

After the first season, he said, there were "some incredibly detailed and lengthy conversations."

There are still surprises and adjustments, simply because producers liked the way an actor and character evolved. The latest example, Cuse said, is pilot Frank Lapidus (Jeff Fahey).

Still, the basics were decided years ago, he said, including the fact that some people would get back to the Mainland. "Otherwise, we'd have 'Gilligan's Island.' "

The producers knew how the story would end, Cuse said, but didn't know when. "We didn't know if we had two years or eight years. For a while we slowed it down; we were on cruise control, which upset some fans."

Then ABC crafted a solution: There would be three final seasons, each with 16 hours, starting in January of 2008.

That plan was jostled by the writers' strike. There were only 14 hours last season, leaving 17 for each of the next two.

The main story was rushed last year, to get the key points into 14 hours instead of 16. A few things were set aside, Cuse said, including what happened to the people on the freighter; "Lost" will get back to them.

Assembling this is hugely complicated, especially since everything — every era, every location on multiple continents — is filmed on O'ahu. "We have 500 people working full time," Lindelof said.

Many others work occasionally. Shows can't afford to keep all actors on hold; some must be urged back when needed. A plot element involving Michael's return was delayed until actor Harold Perrineu was available.

Most actors worry about their characters dying; some are in a more complex situation. Cuse points to the actor who plays Jack's late father in flashbacks: "John Terry's character was dead before the show started, so he doesn't have to worry about it."