“Three Days of Rain” is a terrific piece of theater, perhaps the best yet by Richard Greenberg, America’s reigning writer of erudite entertainments. The 1997 drama crackles with sharp dialogue and even sharper silences, offering sumptuously literate lines and a handful of twists that reward viewers on an emotional as well as intellectual level.

But you wouldn’t know this from the fussy, misguided, occasionally terrible revival on display at the Bernard B. Jacobs Theatre. Shepherded by “It” director Joe Mantello, a trio of movie stars – led by a dismayingly uncomfortable Julia Roberts – have come to town. And a gem of a play has been pretty much slaughtered in the process.

It’s not the first sketchy Broadway production to ill-serve a work by the absurdly prolific playwright (“The Violet Hour” managed that trick three years ago), but it’s the most indefensible one. Mr. Greenberg – to say nothing of the theatergoers shelling out thousands of dollars to see America’s biggest female movie star and her glittery co-stars – deserves better.

The play opens with two siblings reuniting in a Lower Manhattan loft before the reading of their father’s will.Ned Janeway was an architect renowned for co-designing an iconic house on Long Island. The will sat unread for a year while the younger child, Walker (Paul Rudd), left the country without telling anyone. This disappearing act would appear to be par for the course for the scattered Walker, whose life stands in stark contrast to that of his capable and stern sister, Nan (Ms. Roberts), and who takes after their institutionalized mother (“She’s sort of like Zelda Fitzgerald’s less stable sister”).

Even more stalwart than Nan is the dependably dependable Phillip “Pip” Wexler (Bradley Cooper), whom Walker describes as “my late father’s late partner’s torpid son.” Pip got along well with the elder Janeway, is paid a lot of money to act “shirtlessly” on a soap opera, and – most unforgiveably, from Walker’s perspective – has a healthy outlook on life. His arrival, along with the hold he has had on both Walker and Nan in the past, unleashes a torrent of resentments among the three heirs.

The Janeway children always found their father to be taciturn to the point of muteness: “Maybe he was lovable in a Chaplinesque way,” the unforgiving Walker mutters. And the discovery of Ned’s journal, with its terse, unwelcoming comments (including the characteristically spare entry that provides the play’s title), only frustrates them further.

But the second act, which vaults back 35 years to a pivotal stretch in their parents’ professional and personal lives, confounds these assumptions in surprising and wonderful ways. (Santo Loquasto’s handsome set serves both time periods well, aided by Paul Gallo’s painterly lighting.) With an expert ear for the tiny moments on which entire lives can turn, Mr. Greenberg shows how the children understand less about their parents as they learn more. Ned (Mr. Rudd again) and Theo Wexler (Mr. Cooper) are finding their way into the rhythms of a working partnership, a contentious dynamic that is exacerbated by the presence of the fragile Lina (Ms. Roberts) in their lives.

These parallel story lines lend themselves to any number of rewarding approaches. Unfortunately, Mr. Mantello opts for a fidgety, disconnected direction from the play’s very first few moments. The brother-sister dynamic is a painfully broad contrast right out of a scene-study class, with the shameless Mr. Rudd rocking, flailing, and grimacing alongside a mildly compelling (if barely audible) Ms. Roberts.

When Nan looks at the brother she had given up for dead and says, “I could strangle you with my bare hands,” she might as well be asking a bus driver for a receipt. And when Walker says, “You live in Boston,” just a few lines later, he might as well be preparing to either rob or throw himself under that bus, whichever would make for a bigger fracas.

At least Mr. Mantello (who also chose the easy route earlier this year in another starry revival, “The Odd Couple”) seems to realize that, given the inflated ticket prices, having more than one terrible performance per act might be pushing it. And so Mr. Rudd – who actually fares moderately well with his Act II character, the bashful, stammering Ned – lets his leading lady take over the mannered, unconvincing work after intermission. Ms. Roberts’s Nan may have been awkward, but her Lina borders on embarrassing. Drifting in and out of Lina’s Southern accent, grasping at any “playable” sign of mental illness, Ms. Roberts works her way around the stage with the self-consciousness of a homecoming queen being forced to stand up and play Blanche DuBois in English class.

The charming Mr. Cooper is forced to split the difference between these two acting extremes in each act, a feat he manages with only a few lapses. Granted, he acts with his hands too much at first – but Pip is a soapopera actor, after all. Mr. Cooper actually makes being a nice, placid, content guy seem like fun, and he anchors the 1960 material as a charismatic, aloof man whose insecurities bring the future Mr. and Mrs. Janeway together. He and Ms. Roberts have no sexual chemistry in either of the two acts, which hurts the play, but their tender scene together in Act I does seem to set her at ease.

“I don’t waste words,” Lina explains to Ned early in their awkward courtship. “I can’t afford to.” Well, Mr. Greenberg can afford to waste them, and he does so with giddy abandon. In Act I, when Pip finally gets a word in edgewise, he accuses Walker of establishing a “kind of tyrannical psychosocial, you know, fiat.” Bear in mind that Pip, among the three heirs, is considered the dumb one.

If one of Mr. Greenberg’s characters were to score a mere 1500 on the SAT’s, he or she would have some explaining to do. Once you file that information away, it’s easier to roll with the references to Quattrocento and Demosthenes and Heidegger and Oedipus. (Pip’s philistine analysis of the Oedipus story is particularly funny.)

And Mr. Greenberg understands that this linguistic precocity conceals as much as it explains. In one of the play’s highlights, Walker and Nan share the telling of the time a distraught Lina raced out of her apartment, down the stairs, and right through the building’s glass facade, with her 8-year-old son close on her heels. Here’s Walker describing the memory: “There was this moment, before the blood started, when she looked like something crystal. Then bam! – colorized – this sudden redness, everywhere.”

Walker’s sharp imagery and erudition, of course, haven’t prevented him from fleeing – at considerable cost to himself and to others. And how does the centered, melancholy Nan recount the evening? “I called the ambulance, dried the glasses from dinner, and sat on the long, steep, uncomfortable couch. Waiting. I was 10.”

As soggy as Mr. Mantello’s take may be, the intoxicating gleam of Mr. Greenberg’s writing can’t help but poke through the murk. Listen, Sean “Puffy” Combs was pretty bad in “A Raisin in the Sun,” but Phylicia Rashad’s and Audra McDonald’s magnificent work would never have reached Broadway if Mr. Diddy hadn’t made the play a salable property. And if it takes a mega-movie star to get “Three Days of Rain” heard, even one who can scarcely be heard in the fifth row, that may be a deal worth making. She’s not that bad. And the play is that good.

Open run (242 W. 45th Street, between Broadway and Eighth Avenue, 212-239-6200).