She was a cult sensation, from private-club recitals in the 1920s to her final, sold-out Carnegie Hall concert in 1944. And her tale is told on stage in Souvenir: A Fantasia on the Life of Florence Foster Jenkins by playwright Stephen Temperley. It's the astounding tale of a wealthy arts patroness who turned into an opera diva — but who  could not sing a true note.

The 2016 movie Florence Foster Jenkins is wider in scope.  Directors love those close-ups of Meryl Streep, and the movie captures the dynamic bustle of New York City in the '40s.  But the theater experience achieves its own effects no movie could match.

Director Debi Marcucci takes full advantage of the intimate Independence Studio on 3 stage at the Walnut Street Theatre. Scenic designer Roman Tatarowicz creates an elegant drawing room that doubles as concert stage, thanks to the offset sound design of John Kolbinski.  The focus narrows to two characters: Jenkins and her longtime piano accompanist, Cosmé McMoon.

Jonas Cohen plays Cosmé, a cafe pianist who recalls his life with Jenkins. You see how deeply invested they became, and you sense that Cosmé never got over Jenkins' death. Still, it is a relief to hear Cohen's stylish versions of "One for My Baby" and "Crazy Rhythm" after enduring Jenkins' coloratura soprano arias.

Their relationship is deliciously ironic. There are many sides to Cosmé, but he becomes a straight man to Jenkins and her salient trait: refusal to acknowledge she cannot sing. She makes an art song out of denial.  With virtuoso resourcefulness, Rebecca Robbins plays Jenkins' reactions to criticism as bemused, aloof, scornful, pitying, hurt, and often merely nonplussed. Robbins also shines in song. Only an accomplished artist (Robbins studied at Curtis) could sing this badly. And she is close to the real Jenkins sound. (You can hear Jenkins on YouTube.)

The end of Souvenir is incredibly powerful. Unlike the movie, in her final Carnegie Hall concert, you feel you are in the audience. You see Jenkins' charming bashfulness at your admiring presence. She changes costume with every song, becoming a mantilla-clad señorita in "Serenata Mexicana" and a rifle-toting GI in "Praise the Lord and Pass the Ammunition" (costumes by Amanda Wolff). The audience cheers her on as she sings "Adele's Laughing Song." And when the performance ends in a disastrous encore, you feel her numb devastation.

Back in the piano bar and years after Jenkins' death, Cosmé still thinks about her. He thinks about Jenkins' deep love of music and wonders what she truly heard when she sang. As he softly plays "Ave Maria," Jenkins steps back on stage, and in a moment of sublime apotheosis, she tells him.

Souvenir. Through Oct. 15 at the Independence Studio on 3, Walnut Street Theatre, 825 Walnut St. Tickets: $57. Information: 215-574-3550, walnutstreettheatre.org.