Theater is immersion. So when some chump a few rows over is making moment-killing noises during a show — whether that’s pneumonic coughs or ill-timed whoops of praise — standard protocol is to give them the stink eye.

Sing it · Angela Robinson as Shug Avery leads the cast of The Color Purple in “Push Da Button,” one of the production’s most soulful tunes. - Photos courtesy of Broadway L.A.

I have never known an exception to this rule. I like my theaters kept relatively silent, especially at emotional high points, so that I can stay completely in the moment. Even in musicals, there is a time to clap and a time to pipe down.

Except this once — a moment of unbridled spontaneity from an over-rambunctious woman that summed up a near-perfect night.

It was act two of The Color Purple at the Pantages Theatre. Fantasia Barrino, playing Celie, was wailing through her climactic solo, “I’m Here.” After a particularly big note — a soul-piercing cry of pain overcome, impeccably belted — a woman sitting somewhere in the front screamed out, “That’s right, Fantasia. Sing it, girl. You sing!”

I was for a second furious that someone would spoil my special moment. Barrino was singing to me, not to that obnoxious woman, whoever she was. But before she could open her mouth again to finish the song, I realized my fury was born of pure selfishness. Almost immediately, it was replaced by radiance, and I started smiling uncontrollably.

Barrino was killing it onstage — she plumbs a depth of pain and depravity scarcely seen in these sorts of commercial productions. Something obviously resonated with the shouter in the front, and she couldn’t contain her enthusiasm. Who was I to give her the stink eye?

Live theater is a group experience. People who think otherwise, I learned, are seriously missing out. Once I embraced the rowdy crowd, the experience — already powerful — became unforgettable.

As it happens, it was the best crowd I think I’ve ever been part of — a fact I can only attribute to the success of this show. It’s the second iteration of Alice Walker’s Pulitzer Prize–winning epistolary novel (Steven Spielberg’s film was the first) — this time given the Broadway musical treatment.

People like to act pretend-shocked that such a serious story had been musicalized, but in reality it wasn’t much of a stretch. Spielberg’s film has musical sequences that work splendidly, especially the one where Shug Avery (played by a sultry Angela Robinson) marches to her father’s church. Oddly enough, that scene isn’t in the musical. In fact, Shug’s reconciliation with her father, a subplot found nowhere in the book, is barely mentioned, which makes one wonder why it was included at all.

The show’s basic problems can be traced back to its overstuffed script: It smashes together two warring sensibilities — Walker’s and Spielberg’s — and so inevitably misrepresents both. The uneven narrative, moreover, can’t find a rhythm and the episodic structure of the novel is carelessly executed. Temporal coherence is evidently not a priority for these scriptwriters; chunks of time pass by vaguely and unexpectedly and nothing seems to flow particularly well.

Also problematic is the start of the second act: a prolonged African dance sequence that probably looked exciting on paper but in reality is messy and unnecessary.

Despite these obvious shortcomings, the show is salvaged by the remarkable strength of its female performances, particularly Barrino’s. Celie’s story starts off pretty pitifully. She is carrying her own father’s child, and when it is born Pa steals him from Celie’s loving arms and gives him away.

Pa then forces Celie to marry Old Mister Johnson (Rufus Bonds Jr.), a mean man with an eye for Celie’s younger sister, Nettie (La Toya London, an enchanting, underutilized vocalist). Nettie is the only ray of sun in Celie’s ever-darkening night. Johnson, once rejected by Nettie, kicks her out. Nettie is ripped kicking and screaming from Celie’s arms but not before she promises to write.

“Nothing but death will keep me from it,” she cries.

Years pass, and no letters arrive. Celie takes her sister for dead and her life for meaningless. She thinks God and humanity have given up on her — or never cared in the first place. Of course, she is wrong, but she only learns that later.

The arrival of jazz singer Shug, Old Mister Johnson’s somewhat still-burning flame, awakens something in Celie she never knew was there. The relationship that blossoms between Celie and Shug — fleshed out in the book, sheepishly alluded to in the movie, acknowledged in the musical — forms the emotional center of the play. Robinson’s Shug is sweet but not sentimental, and her voice is so bluesy it makes you heartsick.

Other performances that stand out include Felicia P. Fields as the unconquerable Sofia, a Theatre World Award-winning role that she originated on Broadway, and Stu James as Sofia’s charismatic man, Harpo. The other men are comparatively weak. Rufus Bonds Jr. is an unstoppable vocalist but can’t find the right tone and David Aron Damane as Pa tries too hard.

But this is Barrino’s story, and she is unmatched in believability, power and intensity. Her somewhat polarizing voice — some can’t stand it, others say it’s on par with the best there ever was — takes some warming up to, but the payoff is show-stopping. There is, if it’s possible, a sort of effortless strain to her singing, an inbuilt emotional rawness that can’t be faked. Where others sing words, she feels them. “I’m Here,” a soaring ballad that marks a turning point in her life, is alone worthy of a standing ovation.

The soundtrack is churchy like you wouldn’t — or maybe would — believe, and I mean that in the best way possible. The gospel chorus gets a number of well-deserved laughs, and the religiosity never feels overbearing. The only problem is the poor sound. Whether it’s a problem with the Pantages’ acoustics — which are normally fine — or enunciation, I’m not sure, but it makes catching the subtleties and a few important plot points nearly impossible.

The Color Purple is flawed, that’s for sure, but that doesn’t stop the tears from flowing, the spirit from rejoicing or the soul from expanding. Seek this show out, and when Barrino takes center stage for “I’m Here” do everyone a favor and cry out, “That’s right, Fantasia. Sing it, girl. You sing!”