Stephen Sondheim's rewrite of his long-unproduced 1954 musical, Saturday Night, has its American premiere May 19 in Chicago, sporting two new songs and an edited script.

Sondheim attended dress rehearsals May 13 at the tiny, non-Equity Pegasus Players, giving notes, telling theatre stories and eating Chinese food with the cast. Pegasus executive director Arlene Crewdson called it a high point in her career and in the life of Pegasus, a frequent producer of Sondheim's shows. "He was so sharing and caring of everybody," she said.

The musical, about pals, their dreams and their gals in Brooklyn in 1929, was to have been Sondheim's professional debut in the mid-1950s, but a production was thwarted by the death of the producer.

Pegasus Players began previews May 14 for the rewritten version of the thwarted musical. The show continues to June 27.

Lauded Chicago-area director Gary Griffin (Off-Broadway's Beautiful Thing) stages Saturday Night, which features new orchestrations (for 10 pieces) by longtime Sondheim collaborator Jonathan Tunick and a script revised since the 1997 world premiere by the Bridewell Theatre Company in London. The new script, on which Sondheim has worked on since the spring 1998 announcement of this U.S. premiere, includes two new musical scenes, "Montana Chem" and "Delighted I'm Sure." Tunick was in residence there for two weeks. Sondheim visited for a day.

When Sondheim sat at a piano to demonstrate how he wanted one song's ending to be played, Crewdson was floored. She told Playbill On-Line: "In my whole entire life, I never thought I'd see Stephen Sondheim sitting at the piano, plunking out a song with Tunick standing beside him."

The show's book is by "Casablanca" screenwriter Julius J. Epstein, drawn from the play, "Front Porch in Flatbush," which he penned with his brother, Philip G. Epstein. In its 1997 London premiere, the show ran three hours, according to director Griffin, and Sondheim's cuts make the show run less than two hours.

"Our ticket sales are really good," Crewdson told Playbill On-Line. "We have an advance sale -- 100 percent more than we ever had. We're selling tickets all over the world. We are up to 5-6 foreign countries. We had a group sale from Germany of 26 tickets, and requests from 14 states."

*

Pegasus, which has a long association producing works by Sondheim, including the more obscure Anyone Can Whistle and The Frogs, approached Sondheim several years ago about staging Saturday Night, but Sondheim was not ready to revisit the material. After the London staging, Pegasus director Crewdson asked him again about a Chicago staging and he agreed. Rehearsals began there April 12.

Musical director is Tom Murray. The cast includes Elic Bramlett, Ian Brennan, Philip Dawkins, Samantha Fitchen, Chuck Karvelas, Susan Kokot, Christopher LaDuca, Harriet Nzinga Plumpp, Patrick Sarb, Bill Tisdale and Elizabeth Yeats. Designers are Jeff Bauer (sets), Shifra Werch (costumes) and Shannon McKinney (lights).

The story follows lower middle-class Gene and his buddies as they attempt to invest in the stock market, pay rent, sneak into debutante parties at the Plaza Hotel and struggle with the responsibilities of relationships.

Newspapers had reported the show was a go in the mid-1950s, with Kiss Me, Kate designer Lemuel Ayers producing. According to the recent "Sondheim: A Life," the biography by Meryle Secrest, Ayers first targeted Frank Loesser for the project, but Loesser was busy, so Sondheim was asked to write three songs on spec. It was agreed Sondheim would write the score and backers' auditions were held. The score was largely finished, but Ayers died of leukemia and the show died with him.

A Funny Thing Happened on the Way to the Forum in 1962 was to be Sondheim's debut as a composer-lyricist, following lyric-writing assignments on West Side Story and Gypsy.

Nevertheless, there are a handful of Sondheim favorites in the Saturday Night score, known because they were interpolated into the revue, Marry Me a Little and recorded on the Varese Sarabande recording, "Unsung Sondheim."

Cabaret singers, Sondheim fans and musical mavens are familiar with "Saturday Night," "A Moment With You," "So Many People" and "What More Do I Need?"

"I'm really charmed by the show," director Gary Griffin told Playbill On Line April 26. "It's a very optimistic and positive look at young people. What this piece really captures is young people and how they're confronting adulthood: The pain of their loneliness and yet how some of that is very funny."

Griffin said Julius Epstein wrote "really interesting people" and the play has "a wonderful texture of Brooklyn and Flatbush."

A longtime fan of Sondheim, as well as a director of Chicago stagings of Company and more, Griffin said it has been an adventure looking for seeds of the composer's later work in that early show. "You listen to something and hear a piece of the future," he said.

Griffin suggests the show might have been seen as somewhat groundbreaking had it been produced in 1955: "It has an anti-hero and goes to some fairly dark place."

"Montana Chem" (as in chemical) is a montage song that covers a lot of plot surrounding a stock investment to be made by the gang of friends. "Delighted I'm Sure" shows the introduction of a new member to the group.

The show includes a "fantasy couple," representing what gang leader Gene wants. "That's one of the things that's important to me in the piece," said Griffin. "There is a kind of man Gene wants to be; that fantasy character is who he is after. That couple has a lot of choreography."

Does Saturday Night have "legs" beyond Chicago?

"I think this show has a great future, particularly among companies of younger actors," said Griffin. "A lot of young companies want to do Sondheim, and this is a perfect show for a young company or a university."

Pegasus Players, which has a 250-seat proscenium space, is at 1145 W. Wilson at the O'Rourke Center on the Truman College campus. Tickets are $15-$24.

For information, call (773) 878-9761.

-- By Kenneth Jones