The Marx Brothers run amuck in the world of opera when Otis B. Driftwood (Groucho Marx) meets aspiring singer Ricardo (Allan Jones), who is determined to win the love of fellow performer Rosa (Kitty Carlisle). Aided by Fiorello (Chico Marx) and Tomasso (Harpo Marx), Otis attempts to unite the young couple, but faces opposition from the preening star Lassparri (Walter Woolf King), who also has his sights on Rosa. Traveling from Italy to New York, Otis and friends rally to try and win the day.