Andris Nelsons and the BSO continue their recent tradition of performing opera in concert with Giacomo Puccini's Suor Angelica ("Sister Angelica"), one of the three short operas composed in the 1910s and known collectively as Il trittico ("Triptych"). The story centers on the title character, who is living in a convent to repent a past sin, having a son out of wedlock. Acclaimed soprano Kristine Opolais sings the role of Sister Angelica in this concert performance. Opening the program is a work almost contemporary with Puccini's, Lili Boulanger's short tone poem D'un Soir triste ("A somber evening"), one of few purely orchestral works completed by this young genius before her untimely death in 1918 at age 24. Also on the program is Debussy's immensely colorful Nocturnes, an 1899 masterpiece of musical Impressionism.