Billy Wilder's Oscar-winning movie "The Apartment" was a big hit in 1960, but its story — the cynical treatment of young working women by older married men — must have seemed kind of cold for the musical stage. But Neil Simon — who wrote the script for its musical adaptation, "Promises, Promises" — knew what to do. He let the leading man, junior executive Chuck Baxter, spend much of his stage time speaking directly to the audience.

It's as if Simon knew that, years later, the thoroughly engaging Ben Nordstrom would come along to play the part.

One of St. Louis' favorite young performers, Nordstrom dances up a storm and sings with unaffected clarity, both talents that "Promises, Promises" puts to fine use. But what matters most is his charm. Bantering with the audience, confessing his secret dreams or struggling with (well-deserved) guilt, he gives us a look at Chuck that we might have deduced from his interactions with other characters. But we don't have to deduce anything because Nordstrom lays it all on the line.

He brings us inside the character and his world and its world, from the very first scene (which includes Chuck's first monologue). As a result, we're rooting for him. Otherwise, that might be hard.

Apparently Chuck is one of the few single men at the huge insurance company where he's climbing the ladder. When married executives need a place to bring their girlfriends, Chuck obliges them, culling professional rewards. Eventually his scheme comes to the attention of snaky J.D. Sheldrake (Michael Halling). Sheldrake, also married, promotes Chuck in exchange for permanent visiting rights with his girlfriend. Unfortunately, she turns out to be the waitress Chuck is falling for himself, Fran Kubelik (Tari Kelly).

Set in 1968 — an era smartly established by the show's creators, director Michael Hamilton, choreographer Dana Lewis and the design team — "Promises, Promises" enjoys a "Mad Men" gloss as well as the murky waters that ebb and flow behind it.

That's a complicated tone, one that's harder for Kelly to achieve than Nordstrom. Fran is a self-destructive young woman who, because of the standards of her day, is expected to seem bright and shiny no matter what. Kelly is very persuasive as bright and shiny, kind of opaque when it comes to Fran's troubling impulses. However, she's a graceful vocalist who does a lovely job with her songs, including an odd folk-style rendition of "I'll Never Fall in Love Again." It will not fool anyone who spent 1968 buying folk albums.

In fact, much of the music is kind of flat. Composer Burt Bacharach and lyricist Hal David were very popular when they wrote the score, but consider a sampling of 1968 releases: Bob Dylan's "John Wesley Harding," Jimi Hendrix's "Electric Ladyland," the Beatles' White Album (to name just a very few). Bacharach and David were a big deal, but they weren't cutting edge and neither was their musical.

On the other hand, the business world of the show is better suited to Bacharach and David than to younger sounds. And other aspects of the era have held up. John Inchiostro's costumes reiterate the gender roles of the era (understated for men, flashy for young women) that define the plot. And the set and lighting, designed by Mark Halpin and Matthew McCarthy respectively, are a wonder.

Thanks to a system of panels awash in changing colors, the show's different locations (the office, Chuck's apartment, etc.) appear and vanish like magic. But we always know where we are, as do the characters in this regimented world. We also know it's all about to change. That's the trouble with modernity. It simply refuses to stay put.