Even though there are big stars in “The Sign in Sidney Brustein’s Window”—the Marvel (among other things) actor Oscar Isaac and the “Marvelous Mrs. Maisel” actress Rachel Brosnahan—the center of the play’s solar system is Lorraine Hansberry. There are few playwrights who, decades after their death, still seem so present and luminous. Hansberry died in 1965, when she was only thirty-four, yet we’re still exploring her continuing impact, still looking to her for illumination. Since 2017, three major biographies and a documentary have examined both her artistry and her activism, and last year the sculptor Alison Saar unveiled a statue of Hansberry in Times Square, which invited passersby to sit with her in quiet, bronze communion. Meanwhile, the theatre world produces Hansberry’s masterpiece, “A Raisin in the Sun,” her drama about housing discrimination in Chicago, over and over (most recently at the Public Theatre in 2022), and directors comb through her short catalogue, hoping to find some hidden diamond that history thought was glass.

Despite the change of setting from Chicago’s South Side to New York’s Greenwich Village, structurally “Sign” follows the approximate pattern of “Raisin”: a young marriage is in trouble, and, for the headstrong husband, some key disillusion looms. Sidney (Isaac) and his often skittish wife, Iris (Brosnahan), are dealing with Iris’s discoveries in analysis, though Sidney, a nervy intellectual who’s contemptuous of psychotherapy, would rather imagine his “Mountain Girl” barefoot on a hillside than listen to her actual complaints. Their cramped apartment is a crossroads, with the door always swinging wide for assorted types, such as their socialist buddy Alton (Julian De Niro), Iris’s conservative older sister, Mavis (Miriam Silverman), and an existentially blasé playwright, David (Glenn Fitzgerald). Discussion is hectic and often circular. After being persuaded to embrace activism in the arty newspaper he publishes, Sidney hangs a campaign sign in his window for Wally O’Hara (Andy Grotelueschen), an appealing populist running for a city post.

Anne Kauffman’s mega-production at the Brooklyn Academy of Music treats the flawed but fascinating “Sign” with the grandeur of a major work, sometimes to its detriment. Isaac and Brosnahan possess a certain Hollywood magnetism, and they enter heavy with glamour, accentuated by the rather too graceful clothes designed for them by Brenda Abbandandolo. The set, created by the Dots design collective, has its own spaceship-style gravity: a huge wraparound metal scaffolding lifts an entire exquisite apartment ten feet in the air, fire escapes extending both above and below. Heft and luxury, though, is a counterproductive approach for this seams-still-showing play. “Sign” is a social comedy that turns abruptly tragic in its last third, and it needs to feel like farce as long as it can, with Village eccentrics popping in and out, clambering on the couch, butting into one another’s relationships. Staging everything inside a Death Star armature weighs that fleetness down.

An essay Hansberry wrote for the Times just before “The Sign in Sidney Brustein’s Window” opened, in October, 1964, explains that the drama is a portrait of the “engagé,” her way of describing the socially conscious but insufficiently radical. “The silhouette of the Western intellectual poised in hesitation before the flames of involvement was an accurate symbolism of some of my closest friends,” she wrote, “some of whom crossed each other leaping in and out, for instance, of the Communist party.” This analysis explains her tart, even bitter tone in “Sign”—social goads are not necessarily supposed to feel good. The group’s Village microworld is diverse, but people switch their tolerance on and off: whether it’s about Alton’s Blackness, David’s queerness, or Sidney’s Jewishness, someone always makes an ugly comment. Hansberry was serious about prodding complacent liberals into action, though, most famously in a 1963 meeting with Robert Kennedy, when she warned him that he needed to make a moral commitment to Black life. The F.B.I. must not have liked that kind of talk, because it had been maintaining a dossier on her since she was twenty-two; when this thousand-page secret file was posted online, in 2015, it became, in an odd way, the first of her recent major biographies.

The original “Sign” ran for a hundred and one performances on Broadway—the final performance was just two days before she died. It wasn’t a notorious failure: reception ranged from stung (“a vicious sitting in judgment on others,” Richard Gilman wrote) to respectfully mixed. Although the political sequences in the BAM production lack the clarity of that Times essay, you do glimpse, obliquely, what life might have been like for Hansberry herself in her earlier Village days. She suffered from stomach ulcers, just as Sidney does; she was married to an idealistic Jewish man, just as Iris is; she was a gay playwright, a little like David. And her picture of being a woman in that world is drawn in fire.

Iris, Mavis, and their third sister, the late-appearing Gloria (Gus Birney), a call girl, have a collective witnessing-and-suffering function: their last name is Parodus, which, Mavis tells Sidney, is the ancient Greek term for “the chorus,” as in a group of performers who comment on the action. (It’s actually a term for a type of choral ode, but Sidney wouldn’t know that, either.) Here, the sisters are a proving ground for hypocrisy, since the men’s ideals collapse the minute they come into contact with a real, rather than imagined, woman. Alton’s class solidarity can’t expand to include Gloria’s sex work—“I don’t want white man’s leavings, Sidney. Not now. Not ever,” he cries, revolted—and Sidney’s mushy transcendentalism succeeds only if Iris plays his nature-girl prop. A feminist can’t bite into any part of this bohemian sandwich without hitting tinfoil. Wally jokes, “A woman’s place is in the oven,” but Sidney can be worse. After asking Iris for her thoughts on his paper, he snaps at her, “Where did you get the idea you know enough about these things to pass judgment on them?” In a habit that’s excruciatingly recognizable, Sidney also insists on playing his banjo, plinketing and plonketing away when others are trying to talk. That guy.

Hansberry’s touch was shaky in “Sign”: her ear for elevated aria sometimes fails her, her plotting can move in jerks, and she takes weird, self-conscious swipes at David’s avant-garde theatre. Still, she did not write Sidney as quite this irritating. For one thing, he’s supposed to be funny. The script’s character description focusses on his argumentative humor (“a clown—who laughs at himself as much as the world”), but Isaac, ever a leading man, can’t execute the required self-abnegating comedy. Nor is there any erotic spark between Isaac’s Sidney and Brosnahan’s plaintive but oddly inert Iris, so his grabbing at her becomes accidentally unpleasant. We feel ten times more heat onstage when Mavis, supposedly the buttoned-up matron, unleashes a killer monologue, including a blistering diatribe from “Medea”—in Greek. Silverman is as simultaneously regal and foolish here as Lear, and Isaac can be transfixing when he listens, so their scene rockets the proceedings to a thrilling pitch. But, apart from Grotelueschen’s Wally, the rest of the production’s secondary casting works in the other direction. Crucially, the inexperienced De Niro and Birney are out of their depths as Alton and Gloria, whose B plot contains the play’s tragic pivot.

I sound ungrateful, but I’m not. I never thought I would get to see a production of this play. It’s tempting to believe that “Sign” was unfairly maligned by its original Broadway critics, but, truly, it was unlikely to be revived, with its references to long-forgotten Village scandals (there was an original sign in an original window) and its ungainly dramaturgy. Pretending that it’s greater than it is doesn’t do the play any real service; instead, a portentous production obscures those vivid Hansberrian flashes of perception. And this high-gloss, big-name treatment has flattened the part of the show that I did hope would work—namely, its anthropological portrait of a particular milieu in New York. I lost optimism early on in that respect, right when Brosnahan entered. Iris is a waitress, finally off her shift, and she dashes into the apartment’s kitchen, where she whips off her work uniform. Underneath she’s in matching white underwear and tights—everything looking fresh out of the package, since Iris is seemingly the only waitress in history not to have dropped grape jelly on her foot. This Iris appears pristine and camera-ready, and my heart sank. Clean tights in Bohemia? It’s a bad sign. ♦