"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 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 up front,'" 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.

In tonight's episode, titled "The Variable," 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."