She passes the long days of retirement alone in her living room, amidst the doilies and Oriental rugs, the now-silent grand piano. In her prim, sweetly aged voice, she reminisces, periodically reaching into a drawer with a palsied hand to take a cookie from one of her secret stashes. The actress Elizabeth Franz does little more than sit and talk in Julia Cho’s cunningly-crafted new drama, “The Piano Teacher,” which opened last night at the Vineyard Theatre. Yet Ms. Franz’s spellbinding performance as Mrs. K — the play’s haunting, unforgettable narrator — fuels a riveting night at the theater.

For all those who hunger to experience that most elemental of the theater’s powers — its power to engross — Ms. Franz is now giving a master class in how to transfix an audience. Best known for her Tony-winning turn in the 1999 Broadway production of “Death of a Salesman,” Ms. Franz spends most of “The Piano Teacher” dressed in a fuzzy cardigan and orthopedic shoes and ensconced in a cozy armchair. Yet her unprepossessing presence gradually envelops the room. All eyes are focused on her changeable face, which slowly gives out its owner’s secrets; all ears strain in the rapt silence to hear her next word.

An initial series of pleasantries establishes that Mrs. K is, or was: a piano teacher for 30 years; the childless wife of Mr. K, an immigrant from an unnamed war-torn country who dropped the rest of his last name because his suburban neighbors couldn’t pronounce it; the woman who nursed Mr. K in his last months, when he became ill; a lonely widow with no visitors, whose reveries are interrupted only by the television and the telephone; an old-fashioned, upright lady sorrowed by the new generation’s lack of propriety and integrity.

Such keys to Mrs. K’s character increase in importance as the elderly piano teacher fitfully begins to circle around the story of the fateful recital after which all her students quit. Her face is clouded one moment, clear the next. We search it for clues, trying to use our knowledge of Mrs. K to fill in the sizable gaps in her tale.

In this way, Ms. Cho — a talented young playwright and an increasing presence off-Broadway in recent years — merges psychological drama and detective story to unexpected effect. At its best moments, “The Piano Teacher” has the aching weight and mystery of a novel by Chang-Rae Lee.

Ms. Cho opens up Mrs. K’s monologues with visits from two former students (Carmen M. Herlihy and John Boyd), each of whom helps to pry open the piano teacher’s most closely-guarded secret. Stepping into the wallpapered living room, glancing nervously into the adjacent kitchen, where they once waited (supervised by Mr. K) for their lessons, the grown-up pupils infuse the room with a creeping dread. Something surely happened here — something Mrs. K may never be able to confront.

This, ultimately, is the theme of Ms. Cho’s astute exploration of a single heart: our human capacity for self-delusion, the intense desire to not see what lies directly in front of us. For all her generosity of spirit — Mrs. K was, after all, the girl who crossed the college cafeteria to sit next to the lonely recent immigrant — there are murky corners of her own life into which she cannot bring herself to look.

When Ms. Cho’s “Durango” was produced by the Public last season, its material and methods seemed in many ways better suited to the screen than to the stage. It is marvelous to see her tap the unique potential of the theater with “The Piano Teacher,” a piece that fully captures the imagination, working primarily with the tools of a single set and a single voice.

Kate Whoriskey, a sensitive young director with an old soul, has the right touch for the material. She assembles her elements precisely and then stands back to let them work: the radiant, sleepy light in the old parlor; the hint of the kitchen, ever-present; the simple but effective staging; a brief snippet of brooding piano music; the basic but evocative costumes. And if the play’s short coda feels unnecessary, it nonetheless provides a final, indelible glimpse of Mrs. K, one last detail in a remarkable portrait of internal strain.

Until December 9 (108 E. 15th St., between Union Square East and Irving Place, 212-353-0303).