Boston Midsummer Opera returns for its 12th summer with one of the comic wonders of the operatic repertoire: the 17th and most beloved of Gioachino Rossini’s 40 operas, “Il Barbiere di Siviglia” (“The Barber of Seville”) — the story of how the clever barber Figaro helps the delectable Rosina slip out of the clutches of her elderly guardian into the arms of her beloved Lindoro (really the Count Almaviva in various disguises).

The beating heart of Boston Midsummer Opera, for the past 11 years, has been Susan Davenny Wyner, once a celebrated soprano who sang just about everything from Monteverdi to Elliott Carter premieres and now, after a hit-and-run car accident made her unable to sing, a celebrated conductor and music director.