The Berger Center was nearly filled Sunday as Chamber Music Plus Southwest premiered “Sister Mendelssohn.”

The production, a marriage of music and the spoken word, was easily one of the company’s finest — and that is saying a lot. In four seasons here — Sunday was the opening of the fifth — and more than 30 in Hartford, Conn., pianist Sanda Schuldmann and her cellist husband Harry Clark have brought us plenty to oohh and ahhh about. Clark pens the musical portraits, which focus on a musician or those who influenced him/her and incorporates the music-maker’s famous works.

“Sister Mendelssohn” shines the light on little-known composer Fanny Mendelssohn-Hensel, sister of Felix Mendelssohn. We get to glimpse Fanny’s last day, only we don’t know it’s her last day. It’s just a beautiful Sunday in May as Fanny prepares for the Sunday salon concert in her home.

Actress Talia Shire (“Rocky,” “Godfather”) gave voice to Fanny in a warm and thoughtful reading. Shire, sister of director Francis Ford Coppola and daughter of famed conductor/composer Carmine Coppola, brought a contemporary reality to the role; you got the sense that she connected with the character on many levels.

Early on we get a sense something is happening; Fanny complains that her hands are stone cold and she has suffered a nose-bleed. But she braves through the discomfort, reminiscing about her life with Felix and her other siblings and her father, who informed her that her composing was an ornament in her life, not her life.

Clark and Schuldmann performed the soundtrack, comprised of six of Fanny’s compositions and two of her brother’s. It’s a safe bet that Sunday’s audience had never heard the music, although it has subtle flashes of her brother. Fanny, though, was a bit more melodic and more light-hearted.

Superlatives would not do justice to the Clark-Schuldmann Duo’s performance. The pair played the music with a knowing sensibility and true passion, as if they were on a mission to lead a resurgence of Fanny’s music — one that, we learn in the production, is centuries overdue.

Shire brought a similar passion and mission to her role. At the end of the production, as Fanny dies at the piano and Schuldmann plays her piece “O Traum Der Jugend, O Goldner Stern in F,” Shire came close to tears, as did Schuldmann.

The piece’s surprise was in its ending; although we got a sense of dread, we didn’t see that coming.

The production included a multimedia production of Mendelssohn family portraits by Fanny’s husband, Wilhelm Hensel.

Chamber Music Plus Southwest continues its 2007-08 season Jan. 6 with “Schubert Shadows,” with actor Richard Moll (“Night Court”).