In Milan, wealthy dowager Mrs. Claypool (Margaret Dumont
) has hired sly, wisecracking business manager Otis B. Driftwood (Groucho Marx
) to help her enter society, but he merely helps himself to her money. At dinner in a fancy restaurant, he introduces her to opera impresario Herman Gottlieb (Sig Ruman
). Gottlieb tries to persuade her to hire famed Italian tenor Rodolfo Lassparri (Walter Woolf King
) for his New York opera company, and takes her to watch an opera performance with Lassparri as lead. Claypool is impressed and agrees to hire Lasspari for $1000 a night. Determined to cut himself a piece of the pie, Driftwood decides to sign Lassparri for the New York opera company first, and rushes backstage after the opera to find him.
Back stage, Lassparri is a total jerk who beats his playful, mute assistant Tomasso (Harpo Marx
). He tries to romance beautiful chorus member Rosa Castaldi (Kitty Carlisle
). However, she has two problems with that - first, Lassparri is an arrogant, rude, egotistical brute, and second, she's in love with Riccardo Baroni (Allan Jones
.) Riccardo sings in the chorus, hoping for his break to stardom. Riccardo meets up with his old friend Fiorello (Chico Marx
), Tomasso's partner, who declares himself Riccardo's manager and decides to help him move further in the opera world. Looking to sign Lassparri before Gottlieb gets to him, Driftwood wanders backstage and runs into Fiorello, who claims to be the manager of the greatest tenor in the world. Excited, Driftwood whips out 2 questionable contracts for him and Fiorello to sign- however, due to Fiorello's stupidity and inability to read and Driftwood's sarcasm, a comical scene unfolds where they argue incessantly about clauses stating things like "in this contract, the party of the first part shall be known as the party of the first part" and so on. They end up ripping both contracts to shreds, though they both agree they have a contract. At this point, Gottlieb and Claypool arrive backstage and find Lassparri and sign him up - Fiorello informs a confused Driftwood that HE signed Riccardo Baroni!
Gottlieb prepares to set sail for New York at once with Mrs. Claypool, Driftwood, and Lassparri. Also joining the group is Rosa, at Lassparri's request to have her as a leading lady; sadly, this means leaving Riccardo behind. As everyone boards the boat, Lassparri is begged by the papparazzi to sing for the crowd, but he feigns laryngitis: "Why should I sing if I'm not being paid for it?" Instead, Rosa sings "Alone", a popular love song. Riccardo, on the dock, joins in. While he is singing, Rosa asks Gottlieb to consider bringing Riccardo along. He tells her that Riccardo has a nice voice, but will have to wait until he has developed a reputation.
On the boat, Driftwood finds Rosa crying and delivers to her a love letter from Riccardo to cheer her up. As the smartass conman rides luggage carts to his room, he finds that Gottlieb's set him up in a room no bigger than a storage closet, in which his suitcase takes up half the room. An angry Driftwood opens his luggage to find his clothes gone, and that Fiorello, Tomasso, and Riccardo have stowed away inside: after all, Driftwood DID sign Riccardo to the company. Not wanting to get caught with the illegal stowaways, Driftwood demands the 3 leave: Fiorello will only leave after they've been fed. Driftwood then orders multiple plates of food (with multiple hard-boiled eggs) to the room.
What begins now is the "stateroom scene", one of the most famous comedy scenes of all time. Already crowded in the closet-sized room are Driftwood, Fiorello, Tomasso, Riccardo, and the giant suitcase. Slowly, more people begin crowding in the room: two maids come in to make the bed, the engineer and his large assistant come in to fix the heat, and a manicurist shows up to do Driftwood's nails. The already too-small room becomes too crowded as all this action takes place at the same time, and Driftwood continues to let more people in: a cleaning woman comes in to clean up, a young woman looking for her Aunt Minnie tries to use the phone, and finally, the servers with all the food. All these people try to fit in the room with their seperate duties as a smirking Driftwood remarks, "Say, is it my imagination or is it getting crowded in here?" Finally, Mrs. Claypool comes by and opens the door, and all 15 people come crashing out of the room into the hallway.
That night, there are festivities going up on the ship's main deck, including a big dinner where Lassparri tries hitting on Rosa, who rejects him yet again, and a dance. An honor is given to three famous aviators with large beards, who are traveling to New York City for a large ceremony. Mrs. Claypool tells Driftwood she doesn't want him associating with Fiorello and Tomasso, as they are riff-raff, far below her social class. Meanwhile, bored inside their stateroom, Fiorello, Tomasso and Riccardo sneak up to the main deck and help themselves to dinner. Afterwards, Fiorello starts to play the piano and Tomasso plays the harp, much to the enjoyment of the children on board. However, Lassparri spots the three stowaways and informs the crewmembers: they chase the stowaways and throw them into the detention cabin.
Locked up in the brig the next day, Tomasso plays the harmonica much to Fiorello's annoyance, who throws the harmonica out the window into the ocean. Tomasso jumps out the window and into the ocean to get his harmonica. Driftwood, spotting Tomasso from an open window, tosses him the rope to the anchor. Tomasso grabs on to the rope and is lifted back up on to the ship, landing in the stateroom of the three bearded aviators, who lay in bed asleep. Seeing as how the stowaways are illegally entering the country, Tomasso gets an idea to get them safely into New York City, takes out a pair of scissors, and goes to work...
The boat docks in New York City. When the papparazzi try to get the 3 aviators from their room, Driftwood impersonates as their manager, and takes the bearded "aviators" - Fiorello, Tomasso, and Riccardo wearing the shaved-beards as disguises- off the boat. The 3 real aviators are left tied up and gagged to their bed. The "aviators" and Driftwood are taken to a large ceremony at City Hall, where thousands upon thousands of people stand audience in the city, watching. The Mayor presents the 3 aviators with awards and asks them to talk about their accomplishments. Fiorello gives a fake, messed up speech to the crowds, while Tomasso drinks multiple glasses of water to stall time, leading Police Sgt. Henderson (Robert Emmett O'Connor) to suspect that the trio are imposters. The trio pretend to be offended by the sergeant's accusations and storm off, leading him to apologize to the Mayor and Tomasso. Tomasso hugs him- but when he does, his fake beard comes off, exposing their ruse. Everyone goes mad trying to catch the illegal frauds as they escape.
Word is out all over New York City and on the front page of the next day's newspapers as police look for Fiorello, Tomasso, and Riccardo. Driftwood, hiding the trio in his hotel room as to avoid arrest and deportation, shows the news to them and demands they leave before he gets arrested. Before they can, Sgt. Henderson comes knocking at the door to investigate Driftwood's room. As Driftwood tries to slyly deal with Henderson and make him leave, Fiorello Tomasso and Riccardo hide on the fire escape between the kitchen area and the bedroom. As Henderson moves back and forth between the two rooms, the three stowaways use the fire escape to move furniture from the bedroom into the kitchen, leading Henderson to believe he's losing his mind and gone crazy until Driftwood finally gets him to leave.
The day of the big opera finally arrives: Il Trovatore starring Lassparri and Rosa. As Rosa prepares in her room, Riccardo visits and they reunite. However, Lassparri enters and becomes disappointed when he sees the two together, and angry when Riccardo kicks him out of the room. Meanwhile, Driftwood arrives at the theater and gets a happy reception from the chorus: only for Gottlieb to tell Driftwood that Mrs. Claypool has officially dispensed with his services for associating with the riffraff (Fiorello and Tomasso), and he is fired. Driftwood is kicked down the staircase and thrown out of the theater, now unemployed.
Out of a job, out of money, and kicked out of his hotel, Driftwood is left with nothing else but a bench in Central Park, with Fiorello, Tomasso, and Riccardo still with him. Incredibly resentful of how his life is pretty much ruined, he wishes he never met any of them and to be back in Milan. Rosa shows up heartbroken and in tears: she informs the group that, because she doesn't love Lassparri, Lassparri persuaded Gottlieb to fire her from the opera, and she has been replaced with another diva. Fed up with how far Gottlieb and Lassparri have gone, Driftwood decides enough is enough: he begins to plot revenge, the way only the Marx Brothers can...
That night, crowds have filled the big theater to see the opera. Gottlieb arrives in a fancy suit and enters his office: only to find Driftwood, Tomasso, and Fiorello smoking his cigars and eating his dinner. As he tries to call the police, the three of them knock him out and strip him of his clothes, which Driftwood puts on. Their plan has begun: destroy the opera. Driftwood takes Gottlieb's spot in the box seat next to Mrs. Claypool, and delivers a smart-mouthed speech to the audience as the orchestra gets ready. However, sitting in the orchestra causing trouble are Fiorello and Tomasso, who distract the maestro by tapping on instruments. Gottlieb, having woken up and put on Driftwood's too-small clothes, gets to the orchestra box to catch Driftwood, he jumps out and runs for it. Gottlieb sends his men after him and calls the police.
What happens next is 7 minutes of the most amazing operatic mayhem ever to visit the movie screen.
Fiorello and Tomasso have inserted "Take Me Out to the Ballgame" into the musicians' sheet music. When they reach that point and start playing it, the two begin playing baseball in the orchestra, as Driftwood walks around the audience selling peanuts. Gottlieb chases Fiorello and Tomasso into the storage area under the stage, where they knock him out yet again. Driftwood remains running around the opera house, making snarky comments towards everything as Gottlieb's men chase him.
The curtain rises and the opera begins... with Fiorello and Tomasso in costume on the stage with the chorus. They begin to run amok, ripping off singers' clothing and generally causing havoc in the scene. Sgt. Henderson and his police guards arrive backstage, ready to catch and arrest Driftwood and his illegal friends. They find Gottlieb and wake him up, and inform him that the 3 are still out there, sabotaging the opera. Dressing up in costume, the 2 men sneak on to the stage in the middle of the scene to catch Tomasso. However, he escapes by climbing up the backdrop of the stage and disappearing into the rafters of the opera house. He then begins swinging, Tarzan-style, on the ropes and pulleys backstage. This causes various inappropriate backdrops--vendor pushcarts, trolleybuses, and a battleship--to move up and down on the stage while Lassparri is singing. In one case a backdrop is actually in front of Lassparri. Tomasso then swings directly over the stage, making a daring flying snatch of Lassparri's wig.
The police are chasing him all over the backstage area, also swinging on ropes. When Tomasso is cornered, he jumps directly down a backdrop, tearing it in two. The police corner him on the ground, and he runs/climbs back UP the backdrop, then swings on a rope over to the electrical control panel.
He turns off all the lights. Lassparri, still singing solo despite the chaos, suddenly starts to scream but is silenced. When the power is restored, Lassparri is missing! While it was dark, Fiorello and Driftwood have kidnapped, bound, and gagged him, and put him in a box hanging up in the rafters. The box is held up by the ropes controlled by Tomasso. The 4 are completely out of sight of anyone below.
Gottlieb is in a panic. He needs a tenor for the next song. Suddenly, Riccardo and Rosa walk in. Gottlieb begs Riccardo to sing lead in the opera. Riccardo points out that he "has no reputation," (as Gottlieb had pointed out at the start of the voyage.) He demands that his counterpart in the duet be Rosa, since they have practiced it. Gottlieb has no choice but to put both of them in costume and send them out on stage.
Riccardo and Rosa put on an amazing performance of the sad duet "Miserere". In contrast to the preceding raucous goings-on, the audience now pays rapt and appreciative attention to the new singers. Even Gottlieb is impressed. (Ms. Carlisle and Mr. Jones were classically trained; they did their own singing.) At the end of the song, there is thunderous applause. After Riccardo and Rosa go off stage, Lassparri is released. He angrily demands to go out on stage, saying "I'll sing them an encore that they will never forget." But the audience will have nothing of this. They boo him off the stage. He storms out of the opera house.
Gottlieb's course of action is clear. Riccardo and Rosa will be the new stars of the opera company. After quickly consenting to a few demands--all criminal charges will be dropped, and Driftwood will get his job back--he sends the two back on stage for an encore before the enthusiastic audience. All ends happily, or will end happily as soon as Driftwood, Fiorello, and Gottlieb can agree on a contract. Which requires agreement about the role of the "party of the tenth part."