Mrs Teasdale (Margaret Dumont) is a wealthy woman who is recently widowed. She wants Rufus T. Firefly (Groucho Marx) to take leadership of a small country named Freedonia, which has become bankrupt. If he agrees to take on the job, she will bankroll his leadership and provide financial assistance to the nation.
This is not entirely what Freedonia's neighbors have planned; Sylvania is trying to annex Freedonia and the Sylvanian leader, Trentino (Louis Calhern), is attempting a coup. He wants Mrs Teasdale to bankroll his revolution and so begins to court and woo her, hoping to get his hands on her money. Knowing that she is a supporter of Firefly, he decides to try to dig up some dirt on his counterpart, and sends in two spies, Chicolini (Chico Marx) and Pinky (Harpo Marx) to do his dirty work. However, they are terrible spies. They don't find anything that comes close to being dirt but they do prove themselves adept networkers. They infiltrate the government of Freedonia when Firefly spots Chicolini outside his window, selling peanuts, and makes him Secretary of War.
Firefly's secretary, Bob Roland, (Zeppo Marx), is growing increasingly suspicious of Trentino and his motives. He advises Firefly to get rid of him. He believes the best way to accomplish this is by insulting him, a plan to which Firefly agrees. The plan is also to incite Trentino to use violence so that he can be dismissed. The plan goes awry when the mutual insult-throwing results in Firefly slapping Trentino and not the other way around. The two countries are on the brink of war and it is not their borders, but their mutual wooing of Mrs Teasdale and her fortune that is the tipping point.
Somehow, the ever resourceful Trentino learns that Mrs Teasdale has Freedonia's plans for war in her personal safe; he sends in Chicolini and Pinky to break into the safe and steal them, but Firefly catches Chicolini red-handed. He is put on trial. During the trial, war between the nations is declared and there is an outpouring of war excitement and jingoism. There is song, there is dance, and war appears more like a national festival than a national crisis. The trial is put to one side, and both Pinky and Chicolini join Firefly and Roland in anarchy, resulting in a national state of chaos and mayhem.
Trentino is put into a hone-made pillory and is pelted with fruit. He surrenders, but they have not run out of fruit yet and so refuse to let him out of the contraption. Mrs Teasdale sings the Freedonian national anthem and is pelted with fruit for her performance.
