For Winnie, the post-apocalyptic optimist at the center of Samuel Beckett’s shattering “Happy Days,” the presence of another human “is what enables me to go on, go on talking that is.” These two actions — existing and exclaiming — are all but interchangeable for Winnie; they are all she has left. And the divine Fiona Shaw, who has few peers in locating the flesh and marrow within potentially arid language, brings an almost feral life force to Winnie’s most pedestrian ramblings. As Deborah Warner’s splendid production of this frosty 1961 masterpiece makes clear, oblivion looms on the far side of silence.

Pop psychologists would call Winnie, a middle-age woman capable of mining nuggets of happiness from the most debilitating of circumstances, well-grounded. As Beckett enthusiasts know, this term is demonstrably, cruelly apt for our heroine, who spends the entire play buried in earth, first up to her waist and finally up to her neck. The “evil hours” that she laments in Act 2 have left their mark: Ms. Warner and the set designer, Tom Pye, have created a sprawling deathscape that surrounds Winnie in all directions. The “maximum of symmetry and simplicity” that Beckett requested in his stage instructions has been replaced by slabs of broken concrete, menacing tendrils of rebar, boulders, silt, and a very few bedraggled weeds. A handsome but only slightly less bleak landscape painting hangs directly behind Winnie.

She will never see this painting. It is all she can do to crane her neck and keep an eye on her dissolute husband Willie (Tim Potter), who occasionally emerges from the rubble for a brief round of self-pleasure or even briefer conversation. And so it falls upon her to entertain herself until that “happy day to come when flesh melts at so many degrees and the night of the moon has so many hundred hours.” With little more than the meager contents of her purse and the porous contents of her mind to keep her company, the indomitable Winnie grasps at the smallest and saddest of consolations with a ferocious sanguinity, even as “sorrow keeps breaking in” with jarring force and speed.

Woken each morning by a clangorous bell, forbidden to sleep until nightfall, Winnie devotes much of her energy to parceling out her few activities — the opening of a parasol, the brushing of her hair, the perusal of her purse — while taking care not to complete them too early or too late. (Like a distaff Dr. Strangelove, Ms. Shaw repeatedly enlists her right hand to make sure the left one doesn’t open the bag prematurely.)

In other words, pacing is everything for this “hopeful futilitarian,” to use Robert Brustein’s cherished phrase, and the same holds true for “Happy Days.” The author’s infamously specific stage directions (which tripped up Ms. Warner and Ms. Shaw in a controversial 1994 production of his “Footfalls”) and fragmentary speeches have hog-tied many directors, forcing them into either a willful contrarianism or a slavish devotion to Beckett’s purgatorial cadences. Ms. Warner and Ms. Shaw straddle these two extremes masterfully, coloring firmly within the lines but keeping the rhythms from ever settling into a predictable tempo.

Ms. Shaw’s heavily lidded eyes and restless jaw are crucial in conveying Winnie’s seemingly inexhaustible reservoir of consolations, particularly in Act 2, when these expressive features are all that remain. (And even these are at some risk: The lack of access to her toothbrush has taken a toll on the dazzling smile that she displayed so fetchingly in Act 1.) Whether she is charting the process of an ant, basking in the fading memory of an illicit clinch, or casting a weary eye at Willie’s latest objectionable behavior, the vocally impeccable Ms. Shaw makes Winnie’s immersion seem less like an existential conundrum and more like an agreed-upon handicap. To provide so abundantly capable a woman with all her faculties seems almost unsporting.

With its rich and fully earned humor, this “Happy Days” may be an ideal introduction to those who thus far have remained resistant to Beckett’s prickly charms. (The production is filled with enough gallows mirth, in fact, that the use of the theme song to the 1950s-set sitcom “Happy Days” during intermission is particularly unnecessary.) Ms. Warner takes slight liberty with a minor but pivotal pyrotechnic effect in Act 1, replacing Winnie’s self-immolating parasol with a fireball that bursts forth with shocking intensity. The temperature may not be quite high enough for flesh to melt, and that infernal bell sees to it that Winnie will likely never again see the night of the moon. But an evening spent in the company of this giant of a woman, in all her dithering strength, is a happy one indeed.

Until February 2 (651 Fulton St., between Ashland and Rockwell places, 718-636-4100)