In the serialized mystery, one question looms over all: Where are they?

That single central structure might seem more appropriate for a novel. But the "Lost" head writers, co-creator Damon Lindelof and Carlton Cuse, say the structure they and co-creator J.J. Abrams have devised can sustain tension and suspense for however long the series ultimately runs.

The strategy is to plant many mysteries and to turn the focus to the 40-plus crash survivors of Oceanic Airways Flight 815.

"We're asking many questions," Lindelof says. "There is something in the jungle, which we're not showing you. Kate did something, which we're not telling you. There is a broadcast repeating over and over. What is the source?

"The key in the storytelling is when to answer questions and when to ask new ones. The longer the show goes, the more I hope the audience begins to realize there is no one answer."

The structure gives the writers some advantages:

• An unusually large cast. A 14-member ensemble — now down to 13, as character Boone (Ian Somerhalder) was killed off last week — has given the writers numerous possibilities for character development and relationships. The survivors and their intertwined backstories pace the show. "Most people are watching because of the characters," Cuse says.

• Flashback stories. The flashbacks let the writers create richer characters, new mysteries and revelations. Lindelof says one of the biggest twists before Boone's death was not about the island, but that the adventurous Locke (Terry O'Quinn) used a wheelchair.

• A large collaborative process. A novelist works solo. TV writers are a team, whose efforts are interpreted by directors, editors and actors. An on-camera spark between actors Naveen Andrews and Maggie Grace led writers to create a romantic story for their characters, the Iraqi Sayid and the spoiled Shannon.

• Feedback. Lindelof and Cuse can't dictate when the story ends, but they can adjust based on ratings and other factors, such as Internet chatter. "We're getting feedback from people saying, 'We want more mysteries solved,' " Lindelof says. "Maybe we should answer a couple of more questions than we were actually planning on answering."

ABC has announced that the show will be back next season. High ratings mean "Lost" will last longer, which requires a more gradual pace. On a failing show, mysteries could be resolved in a few episodes, Lindelof says.

Kevin J. Anderson, co-author of "Dune: The Battle of Corrin," marvels at the writers' balancing act.

"I have to say I'm amazed as a writer. How are they going to keep this up?" he says. "They have a foreground story with problems on a mysterious island. But the backstories are just as interesting."

Not everyone believes "Lost" has moved fast enough. Best-selling author Stephen King, an early fan, had concerns, saying the program was "in neutral" in February.

Working Backward

Little about "Lost" is conventional. It started as not much more than a "Survivor"-meets-"Cast Away" concept from then-ABC executive Lloyd Braun; Abrams and Lindelof didn't get a chance to work on the script and casting until other fall pilots were much further in development. In some cases, they worked backward, hiring actors they liked, such as Jorge Garcia and Yunjin Kim, and creating roles (Hurley and Sun) for them.

Early in the season, "Crossing Jordan" alum Lindelof brought on the veteran Cuse ("Nash Bridges," "Martial Law"), who had helped Lindelof get started on "Nash Bridges." Now, Lindelof and Cuse, executive producers with Abrams, oversee daily operations.

Neither Cuse nor Lindelof has worked on a show quite like "Lost." Only a few other shows — such as including Chris Carter's "The X-Files" and David Lynch's "Twin Peaks" — have had such complicated mythologies or mysteries.

But the two aren't troubled about plotting their series in such an open-ended medium. That's how TV is.

"We have to rely on gut instinct. I remember the frustration I felt with 'Twin Peaks' as a viewer. It went from being totally great to totally frustrating, because it just got more and more obtuse," Cuse says. "We're really conscious of our show not doing that."

Cuse and Lindelof dispute a contention they sometimes hear: that they are making up the series as they go along. They say mysteries and answers were part of a show "bible" devised early on. There are explanations for the monster, the polar bear, the hatch in the ground, the French woman and the island itself.

"We have a board in the writers' room with all extant mysteries: What questions are in play? Every time you put one up, you hopefully take one off," Lindelof says. Some answers will come by season's end.

At the same time, Lindelof wants the show to avoid becoming so twist-happy that it obscures the characters and stories.

The cast of "Lost" will keep playing out the many mysteries the writers have in store for a potentially long-running series.

Time and mysteries

Novelists and scriptwriters say TV has advantages and disadvantages for storytellers.

"It's an organic, dynamic process. If something isn't working, you can write a character off" or change a plotline, says novelist Joseph Finder, author of "Paranoia" and "High Crimes." At the same time, "they're dealing with this strange limitation. They don't know how much time they'll get to do something."

George Pelecanos, author of the upcoming "Drama City" and a writer for HBO's "The Wire," says TV can limit a writer's options. When he's writing a book and decides to change a story element, he can rewrite earlier chapters to make it match. Once a development has appeared on the small screen, writers can't undo it.

One big challenge for "Lost" was to get viewers to buy into the idea that people could survive a plane crash on an island but not be quickly rescued. "Once the audience accepts the basic premise that nobody's looking for them, it can become 'Lord of the Flies' with adults," says Peter Lefcourt, a TV writer and novelist whose latest book is "The Manhattan Beach Project." Lefcourt likens "Lost" to ABC's "Desperate Housewives," in that both juggle character stories with ongoing mysteries.

The characters and smaller puzzles help keep the bigger mysteries from becoming a viewer preoccupation. Cuse and Lindelof say "Lost" could continue even after answering the central question.

After the pilot, many viewers asked what the monster is. With subsequent story and plot twists, "I get asked that question a lot less frequently," Lindelof says.

But how long can they balance those elements? Anderson likens the effort to "the guy on the old 'Ed Sullivan Show' spinning all the plates."

"I think they're doing it just right for now. But it's still only three-quarters through the first season. If this was the fourth year and they didn't answer anything, I'd be really impatient," he says. Eventually, "they need to give us profound and fascinating answers."

That's another challenge: making the mysteries' answers stand up to fans' vivid expectations.

Anderson and others say time eventually worked against "The X-Files." In the final years of its long run, some viewers felt the mythology became too complicated and did not provide adequate answers.