The Second City members Andy St. Clair, from left, Amanda Blake Davis, Craig Uhlir, Katie Neff and Paul Mattingly perform at the Flamingo Las Vegas. The troupe will debut its fully scripted show on Monday. Photo by Ralph Fountain.

After four years on the Strip, the Second City comedy troupe is still trying to figure out its audience.

And don't expect the former Klingon who came up through the ranks of their Las Vegas comedy classes to explain it to them.

"This Vegas audience is so mutable and always changing. You can never tell one night to the next what pieces are going to hit and what aren't," says Paul Mattingly, the homegrown member of the quintet, who arrived nine years ago to perform in "Star Trek: The Experience."

"We'll have a three- or four-day run when a scene (the word the performers use instead of "sketch" or "skit") is just out of the ballpark. And then it will be crickets chirping sometimes. You can never predict a Vegas house."

Building a return audience has been an issue since Second City opened at the Flamingo Las Vegas in March 2001. Las Vegas is still the only one of five cities where tourist outnumber residents in a Second City audience.

Though the company inspired "Saturday Night Live" and fed that show performers ranging from John Belushi to Tina Fey, the current cast finds that more often than not on the Strip, "you're teaching the audience what they're watching," says cast member Craig Uhlir.

Seeking the right formula has led to experimentation. In October, the producers decided to abandon the scripted-sketch format -- and, as a result, the performers' Actors Equity union status -- in favor of an all-improvised revue.

Now, a largely new cast and new director Jim Carlson are swinging the other direction: The new show that formally debuts Monday will be almost entirely scripted, abandoning improv "games" in the vein of "Whose Line Is It Anyway?"

This time, the change is more of a response to the cast. "We've been out here and we want a chance to write new material," says Amanda Blake Davis, one of two performers who also were in the improv show.

"Granted, when you're in an improv show you're writing every night, but it's disposable. You'll never see it again," she adds. "This is a welcome change for us, to be able to sink our teeth into some written material that was all our own."

The "fail rate" of improv made Uhlir, the other carryover, worry about people who were seeing their first Second City show. In Chicago and other cities with "an improv community," those shows are late-night or second-stage offerings. "I don't think it went bad," he says. "It didn't blow the roof off the place, but I don't think it took anything away from it either."

Director Carlson had worked with three of the cast members before, and went on a USO tour of Iraq with Uhlir and new cast member Andy St. Clair in late 2004. "They came in with such strong material. This time it was stronger than any improv material," he says.

He describes the new show as "darker and dirtier" than what may have been seen at the Flamingo before. The troupe still finds Las Vegas audiences skittish of overtly political or religious satire, but sex seems universal. "We make fun of men and women, basically. The most universal subject in American culture is that men and women don't really understand each other."

Coming in with almost no knowledge of Las Vegas, Carlson won't say, "a Vegas audience won't buy that" as new sketches are rotated in and out for testing each night. "This process has been, 'Let's not assume a lower level, let's assume a higher level. Let's assume that they can deal with darker things than they're used to."

Despite the inconsistency of its response, "We trust our audience more now. We trust them that we don't have to pander. We don't have to have the lights go down between every scene and have rock music play in order to keep their interest. The material itself can keep their interest."

Carlson has directed the touring version of Second City, and says, "On the road it's their house. In Chicago, it's our house. Here, it may be that it's started to feel like our house a bit. Let's bring to Vegas what we do the best."