The plot is almost nothing: a debate among three men who represent that troyka I just wrote: composer, poet, impresario. Which of their art forms is the best?
The opera doesn't allow any resolution, but it also doesn't shrink from the struggle, which is itself the heart of the piece. Each of them gets their powerful moments of assertion; and none of them wins. But in the meantime, we realize more about how we experience opera: torn among these three poles, blown now by the powerful winds of orchestra and melody, then working our way through the ironies and positions manifest in the words, then throwing ourselves into the theatrical paradoxes of illusion and reality.
At the center of it all is the soprano, of course. Today she was Renee Fleming, coy, passionate, clear and beautiful. All the men in the opera love her. Two of them, the poet and the musician, explicitly court her, demanding that she choose one of them. Whether she's supposed to choose on aesthetic or erotic grounds is never very clear; both are in play through the whole opera.
In fact, art and sex are made pretty much the same in Capriccio. If at the end, the Countess refuses to choose either man as a partner, she also refuses to decide between words and music. She will not say, in the terms of the "plot" (if you can call it one), how the opera is to end.
So after singing her way through her irresolution, she shrugs and goes off to supper. We don't shrug!
Check out just a few minutes of these videos of Renee doing the twenty-minute-long last scene. You'll probably get hooked, too. Will you be hooked on the music, the words, the theater, or the countess, or all of them at once?