LOS ANGELES » “;Lost”; marks its 100th episode tonight, an achievement its producers consider as surreal as the TV drama's mind-bending plots.

Executive producer Damon Lindelof, one of the series' creators, recalled a meeting with ABC executives four years ago to pitch the idea of plane crash survivors stranded on an island of mystery and danger.

They were asked where the “;Lost”; saga would stand at, say, episode No. 74.

“;I said, 'We're probably not going to get past episode 13. Let's all be honest about that upfront,”; Lindelof recalled, adding, “;If I traveled back in time to tell myself after that meeting that we were going to make it to 100 and still have a season beyond that, I would have laughed in my face.”;

Fans will appreciate the notion of time-skipping, since the current season has reveled in just that. “;Lost”; has flung major characters across decades, leaving them—and the audience—feverishly attempting to keep events straight and the end game in sight.

“;It was always part of the master plan that the time-travel elements in the show would become more overt,”; said executive producer Carlton Cuse. He recalled an early episode in which Sayid (Naveen Andrews) is fiddling with a radio and hears 1940s music.

“;That was a signpost we were planting early ... that this island was not in the same place and space time as the real world. We knew that in season five we were going to deploy this and the show would become more overtly a genre show, and we were OK with that,”; Cuse said.

“;We've always felt we had to make bold choices,”; he said, and the audience has responded.

In tonight's episode, titled “;The Variable”; and airing at 8 p.m., viewers will get a few more pieces of the puzzle.

“;We're not promising any big whiz-bang flash pyrotechnics,”; said Lindelof. But it does serve as what he calls “;a companion piece”; to another memorable episode, last season's “;The Constant,”; in which Desmond (Henry Ian Cusick) endured vicious, turbulence-caused side effects.

“;This season has really been about the rules of time travel as explained by Daniel Faraday,”; Lindelof said, referring to the brainiac played by Jeremy Davies. “;We've never done a flashback story for Faraday, so he's very mysterious. Some of those mysteries will be answered in this episode.”;

Viewers also check in on Desmond, wounded in the April 8 episode as he defended his beloved Penny (Sonya Walger) from vengeful, gun-toting Ben (Michael Emerson).

“;We find out whether it's fatal,”; said Cusick, his tone carefully neutral. The “;Lost”; cast is trained to avoid disclosures, but he concedes the show's penchant for killing off characters does take a toll.

“;Every season it's, 'Am I here, or not? Do I pack?' “; Cusick said. “;Ever since Penny and I were reunited, I feel like Desmond's story could easily be done. ... He found what he wanted.”;

But then Cusick suggests there may be more to come. Desmond has yet to confront the guilt of leaving others behind on the island, Cusick said, and perhaps he's among those who must journey back as part of a grand reckoning.

Or not. The actor isn't 'fessing up.

Neither are Lindelof and Cuse, as the two-hour May 13 season finale draws near. But there will be answers someday, they promise.

“;Lost”; is set to wrap after one more season, a decision the producers made to allow for a carefully plotted finale. According to Lindelof, it will be a “;very cool ending, and enormously satisfying.”;