Smash, Katharine McPhee and Megan Hilty

Thanks to NBC's relentless marketing and PR campaign, much is already known about Smash, a big-risk series about the making of a Marilyn Monroe musical. At the center of the sudsy backstage drama is American Idol's Katharine McPhee, who stars as an ingénue pitted against a more seasoned Broadway chorus girl to play the iconic blonde.

If the premise sounds hopelessly niche for a broadcast network in desperate need of a hit (thespians! show tunes! jazz hands!), both NBC and critics high on the series have been working hard to change your mind. Advanced word on Smash is that it's the anti-Glee (especially if you've tired of that show's pop song-happy chorus of high schoolers), The West Wing but on Broadway (should you miss Aaron Sorkin's defining sense of a workplace), and a game-changer for NBC (if you went bananas for the first episode, which NBC screened in theaters and made available on-demand and online weeks before Monday's official premiere).

Watch Smash right now — then tell us what you think!

Is it all just hyperbole? TVGuide.com watched the show's first four episodes, and grilled the creators, songwriters and cast of Smash, to give you the low down on what you can really expect:

No one spontaneously bursts into song. Smash itself isn't a musical. Characters aren't "singing their feelings while skipping down halls," explains series songwriter-composer Marc Shaiman. But in attempting to keep things grounded in reality, the characters do visit one lounge/club/karaoke bar per episode in order to belt off-stage. Whether or not that device will continue beyond the fourth episode remains to be seen, but the producers are already reserving the right to change their mind: Shaiman and writing partner Scott Wittman admitted they are dying to find a real way for Anjelica Huston, who plays the producer of the Marilyn musical, to sing. "I just snuck off with them and we did a recording of something," Huston revealed. "I have a sort of long history of singing; generally, I only do it in the shower, but I love to sing."

But Smash is very inside Broadway. The plotlines -- and here is where those West Wing comparisons come in — revolve entirely around the politics and inner workings of the theater biz: the brutal auditions, creative clashes, endless rehearsals, diva rivalries. New York Post theater critic Michael Riedel gets name-checked as the "Napoleonic little Nazi" villain in the first episode (and he's thrilled about it!) and real-life theater investors drop in for cameos. Huston believes it's a provocative inside look at life on The Great White Way: "The one thing I'm absolutely convinced about is that people love to be on the inside, whether they live in Middle America or not. People like to know the numbers," she said. "They also like to know who's sleeping with whom. It's a sophisticated soap."

Uma Thurman takes the stage for five-episode arc on NBC's Smash

The behind-the-scenes drama is more sudsy than serious. As much as Smash's creative team (executive producers Steven Spielberg, Shaiman and Wittman, Craig Zadan and Neil Meron and creator Theresa Rebeck -- all hard working theater folk) want the series to be authentic to the biz, it seems more important that they "put on a show" themselves. Think of the breezy way Entourage did showbiz, not so much the annotated notes-required way Luck does horseracing. The resulting tone is mostly light and fun, and only occasionally melodramatic.

In Smash, one of the assistants working on the musical is an eavedropping spy; the director is a swaggering ego incarnate who puts the moves on both potential Marilyns; the producer likes to toss Manhattans in the face of her soon-to-be ex; and one of the songwriters is trying to make time to adopt a Chinese baby with her husband while sorting through her feelings about having had an affair with one of the actors in the show. Megan Hilty, who plays one of the actresses up for the part of Marilyn, says the theater world just happens to be "very incestuous, and very gossipy." "You become a family working together, but that's a byproduct," she said.

Don't expect Glee-sized music sales, or fanfare. Smash dabbles in radio hits — Christina Aguilera, Bruno Mars, Michael Buble, Adele, Carrie Underwood, Gretchen Wilson and Blondie covers are mixed in with original show tunes about Marilyn Monroe — but not in the poppy radio-friendly style of the Fox hit. Also unlike Glee, Smash is a 10 pm show aimed at adults, not teens who are more likely to send songs up the iTunes charts. You can color us shocked if the Smash music sells even a fraction as well as the Glee covers do.

Marilyn Monroe is sort of beside the point. The truth is none of the series producers considered themselves well-versed in all things Norma Jean before they decided to make her the subject of the musical. Rebeck says Wittman pitched Monroe during a brainstorm meeting, and she wasn't initially enthused. "I said, 'Oh, I don't know,'" Rebeck recalls, remembering a Marilyn musical that famously flopped on Broadway in 1983. But as they began to research and read about the film icon, they agreed that she led a "very theatrical, very eventful life." "Eventually I had a moment where I finally said, 'I'm not sure I can write a brilliant musical about Marilyn, but I do know I could write a brilliant television show about people trying to write a brilliant musical about Marilyn.'"

Bernadette Peters and Nick Jonas to guest-star on Smash

Acting isn't Katharine McPhee's backup plan. The good news is among a cast of pros, several of whom come direct from the Broadway stage, she doesn't stand out as green. Turns out acting isn't just an alternate road to fame for the 27-year-old Los Angeles native who came up second to Taylor Hicks on Idol. "I've always had a lot of theater and musical theater in my life," McPhee says. She performed in plays and musicals throughout high school, and studied theater in college "for three semesters before I dropped out to go into acting, to be a movie star!" she says, laughing. "Oh, the dream seemed so easy in the moment."

Don't be deceived by Mount McPhee -- casting Marilyn is going to take most of the first season. To hear the theater vets tell it, leading roles are not so easily won -- spoiler alert: later in the first season, watch for Uma Thurman to come in as a movie star also vying to play Marilyn -- so don't read too much into the special attention McPhee's been getting. Says Christian Borle, who plays one of the musical's songwriters: "That is something that drives theater people crazy. If they can bring in a star, they will. It's a question of money. They need people to buy tickets." Hilty says she's been edged out before. "I can't tell you how many times I've done readings and workshops for projects wanting to go to Broadway. You give your life to it and at the end of the development, they're like, 'We love you. You're perfect. No one could do this better than you. But we need a star.'"

It's going to take more than one show to turn around NBC's ratings woes, but it's still bad news if Smash underperforms. In January, NBC Entertainment Chairman Robert Greenblatt said Smash wasn't a "make-or-break show" for the fourth-place network. But tepid applause certainly won't be good considering the failures of The Playboy Club, Prime Suspect and nearly dead The Firm, and just OK viewership for Law & Order: SVU, Grimm and Parenthood. Adding pressure to the performance of Smash is NBC's other, arguably riskier, mid-season series Awake, a somber drama about a man living in a fractured reality after a fatal car crash. That show isn't getting half the promotion Smash did.

And now, a promo featuring the casts of all of NBC's shows — even Donald Trump! — gathered to promote Smash: