Opera, on the whole, doesn’t much go for sequels. After all, the tragic ones tend to kill off their protagonists. And the romantic comedies? The satirist Kurt Tucholsky noted that the fade to dark after a silent-movie happy ending is necessary to spare viewers the spectacle of a marriage filled with “boredom and burnt milk.”

But for some of the best-known characters in opera — Figaro, Susanna, Rosina and Count Almaviva — there is life after the final curtain. These beloved figures populate the trilogy of plays by Beaumarchais that was adapted into Rossini’s “The Barber of Seville” (based on the first play) and Mozart’s “The Marriage of Figaro” (the second).

From Tuesday through next Saturday, On Site Opera presents a rare production — the company says the first ever in North America — of Darius Milhaud’s operatic adaptation of the trilogy’s finale, “La Mère Coupable” (“The Guilty Mother”). No commercial recording exists of this work, which was first presented in Geneva in 1966, and a smut-and-blood staging in Vienna in 2015 didn’t exactly broaden its appeal. Milhaud’s hyperactive score, full of barbed dissonances, certainly does little to endear itself to the listener, and the material is darker than in “Barber” and “Figaro.” As On Site Opera’s music director, Geoffrey McDonald, said recently between rehearsals, “It takes these people everybody knows and transplants them to a Raymond Carver story.”

The plot revisits Count Almaviva’s household 20 years after the turbulent events surrounding the marriage of the count’s barber, Figaro, to the countess’s maid, Susanna. The guilty mother of the title is Rosina, the countess, who is forced to own up to her infidelity with the page Cherubino (now dead), which resulted in the birth of a son, Léon. As in each of the first two plays, an outsider tries to manipulate the situation to his own advantage, and an uncomfortable truth must be faced before a marriage can take place.