Ben Brantley dampened the pages of the New York Times with his enthusiasm for “the self-lacerating vanity” of Ralph Fiennes in last year’s Broadway revival of Brian Friel’s gorgeous 1979 play Faith Healer; critic Michael Billington argued that it was the palpable devotion of Ian McDiarmid’s Teddy who made a 2001 London mounting sing. In the quiet little production Mark A. Rhea has staged for the Keegan Theatre’s new stripped-down theater project, it’s the exquisitely calibrated agonies of the show’s one female character that make the evening, and the extraordinary Kerry Waters Lucas who brings them to life.

Waters, let’s stipulate, has a couple of built-in gifts: a lovely purr of a contralto, a jaw line and cheekbones that constitute little come-hither invitations to lighting designers of all persuasions, and behind her eyes something—damned if I know what—that lends itself equally to vulnerability and fierceness. She struck me as remarkable the first time I encountered her, playing the mischievously malevolent Sphinx in Steven Berkoff’s Greek for Scena Theatre in 1998, and she strikes me that way every time I see her on a stage.

It’s what she does with those gifts here that proves so mesmerizing: Playing the wife (or is it mistress?) of the titular itinerant alcoholic, she deploys that voice and those features and that ineffable something as emotional markers, navigating a 30-minute monologue with as much assurance as any performer I’ve ever seen. With a hardening or a faltering of her tone, a lowering or a sharpening of her gaze, she tacks back and forth across the watery boundary that divides fortitude and despair. And for longer than you’d think possible, she keeps open the question of whether Grace will break—and then she closes it, shatteringly. She alone makes the trek to Gunston Arts Center worth the trip down I-395.

Which is good, because Eric Lucas plays the sick-at-heart Frank quietly—too quietly, perhaps, to convey the magnetism that keeps Grace wavering on that edge or to capture a sense of his weird gift, unreliable as it is—and Mick Tinder makes a bland and not particularly affecting Teddy. The production, never mind that Keegan bills its “new island project” as an exercise in minimalist, character-driven theater, gets in the way occasionally, with unflattering costumes and more prop clutter than seems necessary.

Ah, yes, the play: Three monologues, chronicling Frank’s career and Grace’s sufferings and their end, Rashomon-style, each narrator as unreliable as the next, even though the details of their stories occasionally agree. Lapidary language, a magnificently Irish eccentricity of eye, a mournful sense of how pain lingers in memory. It’s a deceptively simple-seeming thing with a dark and complex heart, and it speaks plangently even in this off-center production.