Verdi’s “Il Trovatore” is one of the most popular operas of all time, and also one of the hardest to follow. What is going on with this crazy plot? There’s a lot under the surface, and it's all spelled out in this explainer by Marc Eliot Stein, who shows how a thrilling but nakedly horrible storyline became an entertainment fit for 19th century operagoers. This fascinating episode ends with a look at the Marx Brothers “A Night at the Opera”, which joyously tears Verdi’s masterpiece to shreds.