What if? It's a short question, something we often wonder throughout our lives (maybe even multiple times each day). On the surface, it's a simple question, too. What if? What if just one seemingly innocuous choice changes your fate—or does it? What if there were a musical that asked us to grapple with this? Then it would be If/Then.

This original Broadway musical, which reunites team Next to Normal, Tom Kitt (music), Brian Yorkey (lyrics and book) and Michael Greif (direction), tells Elizabeth's stories. Recently divorced and in her late thirties, Elizabeth (Idina Menzel) moves back to New York. One friend, Kate (LaChanze), says "Liz" moved to NYC to find true love. Another friend, Lucas (Anthony Rapp), says "Beth" returned to pursue her dream career. (As part of her reinvention, Elizabeth decides between calling herself Liz and Beth.)

At the top of the show, Elizabeth meets up with Kate and Lucas in Madison Square Park and each asks her to tag along for something different that afternoon. If/Then follows Elizabeth on two simultaneous journeys: one in which she chooses to go with Kate and be called Liz, and one in which she chooses to go with Lucas and be called Beth. Liz meets and falls in love with Josh (James Snyder) and Beth forges ahead as a successful city planner.

Mark Wendland's sparse scenic design moves fluidly with the choices, with the skeletal cubes turning to reveal the results of yet another choice. The story is clarified by Kenneth Posner's great lighting design. (Red indicates we're in Liz's story, blue for Beth.) And thanks to Brian Ronan's sound design, you'll be able to hear and decipher all the lyrics, which is key to keeping up with each storyline, even as the orchestra plays.

And that orchestra is playing music written by Tom Kitt, a genius. The way he turns what would normally be a throwaway note or phrase into something much more layered and telling—as if he were changing choices midstream. We are so lucky to be living in a time when Tom Kitt is writing music. What he and Brian Yorkey can do in a song—in a four-minute song—is what some writers take novels upon novels to not even approach. (Yorkey's lyrics and book are poignant and funny.) They way they are able to zero in on the characters' inner monologues and express something deep and human and thoughtful is unparalleled. (I would be remiss if I didn't mention Michael Starobin's expert orchestrations and Carmel Dean's musical direction.) Kitt and Yorkey have written a show that is romantic about New York and all its chances for if/then moments.

Those if/then moments—the simple question, what if?—provoke all sorts of complex, interesting, important questions. Liz, at one point, says that there isn't fate but rather there are probabilities playing out. But If/Then makes you wonder if she's right. Lucas and Beth speak of "other me"s, other versions of themselves that are experiencing different lives. I'm not sure who is right. What if there were something unchangeable about us? What if it's not about our choices? What if, no matter the choices we make, certain things and certain people are destined to be in our lives? 

Aside from those questions, If/Then has plenty to brag about. The creative team, as mentioned above, is on point, and the game cast does terrific work. The ensemble, which includes Miguel Cervantes (American Idiot) and Ryann Redmond (Bring It On), is filled with versatile performers, all of whom portray multiple characters. Jenn Colella (Chaplin), Jason Tam (Lysistrata Jones) and Jerry Dixon (tick, tick...BOOM!) offer great support as people who come in and out of Elizabeth's life, depending upon the choices she makes. LaChanze (The Color Purple), James Snyder (Cry-Baby) and Anthony Rapp (Rent) all excel in pivotal roles.

But the star of the show is Idina Menzel and what a star she is. Returning to Broadway after ten years, the Rent and Wicked star gives a master class with her performance. ("Always Starting Over" slew me—what was coming out of Idina's mouth will give you chills.) I don't even have the appropriate words to describe what it's like to see such a raw, honest performer show you what it means to be that good at your craft. And she does it in a way that does not say, "Look at me, I'm acting and singing really well." Instead, her performance is natural and she fully embodies Elizabeth.

An original musical. I'm so grateful to be seeing theatre now. Many people look to the past as the heyday of American musical theatre and while not everything that comes to the stage in a given season is great, we remember the gems. If/Then is one of those gems. Bravo to the team for bringing something challenging and complex to Broadway; something provocative (but not necessarily salacious); something that is funny and touching and honest; something that boasts a strong woman at its center; something that is based on nothing more than an idea (or a question); something with an entirely original score; and something that stars performers truly up for the task at hand, rather than matinee idols or other marquee names who are only serviceable. If/Then is why I love musical theatre—why I love the power of the theatre, of going on a journey—two journeys, in fact—with someone, connecting with her and letting go of my inhibitions enough to be moved by her.

What if all theatre experiences were like this?

If/Then is now playing at the Richard Rodgers Theatre. Visit ifthenthemusical.com to learn more and to purchase tickets.