In a recent release announcing a special performance that was held Tuesday evening at the Oliver Wolcott Library, the organizers said, in part, “One doesn’t need to understand French to feel the power, passion and beauty of their music.”

A skeptic might shrug in disbelief and call it hopeful hype. But only moments into the performance by international film star Irène Jacob, her brother Francis and their backup musicians, it was clear that no hype was involved.

As a vocalist, Ms. Jacob is witty, funny, beguiling, persuasive, charming, melodic and more; quietly beautiful, mesmerizing and hypnotic. (And the English translations of the song lyrics that were handed out helpfully put it all into context.)

In presenting this nonpareil concert, the library partnered with the Alliance Française of Northwestern Connecticut, whose president, Marcy Jackson, admitted in her introduction Tuesday to not immediately recalling Ms. Jacob’s stature and film accomplishments when first contacted by Francis about the siblings’ new CD, “Je Sais Nager.”

But between making contact with Francis and the concert this week, Ms. Jackson and her legion of Litchfield County Francophiles made sure to screen the French films for which Ms. Jacob is most famous, “The Double Life of Vèronique,” and “Red.”

“This musically gifted duo began writing their repertoire after the passing of their father in 2007,” the release announcing the sold-out concert had explained. “Although they live on two different sides of the Atlantic, they have always had a drive to write songs together and bring them on stage. Their modern day collaboration relies on communicating through e-mails and Skype and today they freely write with four hands. For both of them this musical venture is a sacred privileged space where they can meet and create a new virtual life somewhere between Brooklyn and Paris. Francis will complete a phrase Irène left unfinished and adapt her voice and words to his compositions and arrangements, [and] Irène, in turn will fit her voice around his blended rhythms. Together their compositions create a unique sound of soft, rhythmic melodies that delight, transport and uplift the listener. One doesn’t need to understand French to feel the power, passion and beauty of their music. A sample of their songs can be heard at myspace.com/ifirenejacob.”

Ms. Jacob was awarded the Best Actress prize at the 1991 international Cannes festival for her performance “Vèronique.” Other credits include “Rio Sex Comedy,” and “U.S. Marshals.”

As a vocalist, she has recorded with the National Jazz Orchestra, French star Vincent Delerm and Brazil’s Richardo Tete, among others.