Stuck at the Crossroads Between Fate and Choice

New York City has never looked cleaner than it does in “If/Then,” the gleaming drawing board of a musical that opened on Sunday night at the Richard Rodgers Theater, starring the shiny-voiced Idina Menzel.

Actually, to find any urban environment that is this spick and span, you’d need to look back to the 1970s, when Mary Tyler Moore conquered Minneapolis on television. The nearest contemporary equivalents are those commercials in which peppy young things go dancing in the streets to trumpet the virtues of cars and colas.

But even they — and “If/Then” does bear a passing resemblance to such ads — lack the antiseptic sheen of this production, written by Tom Kitt and Brian Yorkey, with direction by Michael Greif, the team that gave us the four-handkerchief triumph “Next to Normal” several years ago. Every surface here appears to have been so thoroughly polished that you could not just eat off the sidewalks but see your own reflection in them, if you so chose.

The show’s protagonist, Elizabeth (Ms. Menzel), a conflicted city planner, so chooses. Manhattan is her mirror, a place to regard herself, not only as she is but also as she could have, would have and possibly should have been. It feels right that Mark Wendland’s set includes a mirrored ceiling to reflect and multiply the actions onstage.

“If/Then,” you see, is a portrait of alternative existences, of roads taken or not, of the person a person might have been if she had only done this instead of that. If that sounds confusing, don’t worry. You may occasionally have trouble keeping the show’s twin story lines separate. But you’ll never be in any doubt whatsoever as to what the central theme is.

That’s because Mr. Kitt (music) and Mr. Yorkey (book and lyrics) never let us forget. Until the show’s last quarter, when some shadows darken the bright emotional landscape, all the songs are pretty much interchangeable. Whether performed as solos or ensemble pieces, these numbers tend to percolate along, blithely and wonderingly, at the speed of circular thought. They also put to work every metaphor you’ve heard about the elements of fate, chance and choice that govern our lives.

Allow me to quote a few titles: “What If?,” “You Never Know,” “It’s a Sign,” “Surprise,” “Some Other Me” and “What Would You Do?” The lyrics of such songs are about what you’d expect, as in, “You lose all the choices you don’t get to make/You wonder about all the turns you don’t take.”

I chose that quote at random (unless you don’t believe in randomness, or choice, a subject of some debate in “If/Then”). Such words are largely set to folk-inflected pop melodies that have the insistent, mildly agreeable patter of a gentle spring rain. (The appealingly light-footed, urban-flux choreography is by Larry Keigwin.)

The homogeneity of the numbers creates the effect of a sort of songwriting tutorial by rote. At intermission, I found myself continuing in the vein of Mr. Kitt and Mr. Yorkey, chanting little ditties of my own like, “I’m driving on the Thruway, take the ramp that’s on the left, I wind up in Elmira….”

But I digress. (See what you made me do, “If/Then”?) Back to the plot(s): Elizabeth, hitherto a college professor of urban design, is newly divorced and newly arrived in Manhattan from Phoenix, with dreams of an exciting new career. Or an exciting new romance. “If/Then” wonders, none too originally, if it is possible to have both.

So Elizabeth splits into two people, Liz (who wears eyeglasses) and Beth (who doesn’t), who pursue separate paths from the same starting point, Madison Square Park, on the same day. It’s there that Beth takes a call on her cellphone from a now-powerful school chum (Jerry Dixon) that leads her to a meteoric rise in city politics. Liz ignores the call and has a chance encounter (or is it?) with Josh (James Snyder), a handsome doctor in Army fatigues, who has just completed a tour of duty.

Another point of the show is that every individual life is contingent upon the shifting existences of others. This means that Elizabeth’s choices affect the futures of her close friends Lucas (a low-key Anthony Rapp), an idealistic community activist of ambivalent sexuality, and Kate (an utterly charming LaChanze), a contentedly lesbian kindergarten teacher. (The equally cute Jason Tam and Jenn Colella play the significant others in their lives.)

The premise of “If/Then” recalls “Sliding Doors,” the 1998 movie in which Gwyneth Paltrow led parallel lives with different hair colors. But its conceptual novelty factor aside, “If/Then” more exactly resembles a Lifetime movie — or two Lifetime movies spliced together — the kind in which prominent television actresses, in between crime shows, portray women whose lives are forever altered.

Taken separately, neither plot of “If/Then” is terribly compelling or distinctively drawn. Taken together, they feel less like variations on a theme than dogged reiterations of a theme.

Yet I suspect this show, which has been doing solid business in previews, will have no trouble finding an audience. Ms. Menzel, who brings an anxious intensity to a featherweight part, has an enviable fan base among young female audiences. She won fame (and a Tony) by originating the part of Elphaba in the long-running musical “Wicked.” (Her celebrity quotient has been raised by the use of her voice in the hit animated film “Frozen” and her performance this year at the Academy Awards, when John Travolta’s mispronunciation of her name went viral.)

In “Wicked,” a tale of two witches that riffs on “The Wizard of Oz,” Ms. Menzel played Elphaba, a green-skinned outcast who discovered her inner power — and the highest human decibel level Broadway had known since Merman. Though in “If/Then” she keeps tight reins on the volume until a smashing climactic lament in the second act, young theatergoers who identified with her Elphaba will probably identify with her Elizabeth, too, now that they’re a bit older.

Like Elphaba, Elizabeth is prickly, smart-mouthed, loyal and neurotic. Despite her doubts, she gets what she wants, even if she doesn’t know what that is. She also gets a whole, bustling city as her private introspective playground. In this rendering, that’s a place so improbably uncluttered and streamlined that a gal can use it as a blank slate, or perhaps Filofax page, to map out her existential choices.