The play begins with Dikaiopolis sitting all alone on the Pnyx (the hill where the Athenian Assembly or ecclesia regularly meets to discuss matters of state). He is middle-aged, he looks bored and frustrated and soon he begins to vent his thoughts and feelings to the audience. He reveals his weariness with the Peloponnesian War, his longing to go home to his village, his impatience with the ecclesia for its failure to start on time and his resolve to heckle speakers who won't debate an end to the war. Soon some citizens do arrive, all pushing and shoving to get the best seats, and then the day's business begins.
A series of important speakers addresses the assembly but the subject is not peace and, true to his earlier promise, Dikaiopolis comments loudly on their appearance and probable motives. First of all there is the ambassador who has returned from the Persian court after many years, complaining of the lavish hospitality he has had to endure from his Persian hosts; then there is the Persian grandee, The Eye of the Great King, Pseudartabas, sporting a gigantic eye and mumbling gibberish, accompanied by some eunuchs who turn out to be a disreputable pair of effete Athenians in disguise; next is the ambassador recently returned from Thrace, blaming the icy conditions in the north for his long stay there at the public's expense; and lastly there is the rabble of Odomantians who are presented as elite mercenaries willing to fight for Athens but who hungrily steal the protagonist's lunch. Peace is not discussed. It is in the ecclesia, however, that Dikaiopolis meets Amphitheus, a man who claims to be the immortal great-great-grandson of Triptolemus and Demeter and who claims, moreover, that he can obtain peace with the Spartans privately. Dikaiopolis accepts his claims, and he pays him eight drachmas to bring him a private peace, which in fact Amphitheus manages to do.
Dikaiopolis celebrates his private peace with a private celebration of the Rural Dionysia, beginning with a small parade outside his own house. He and his household, however, are immediately set upon by a mob of aged farmers and charcoal burners from Acharnae – tough veterans of past wars who hate the Spartans for destroying their farms and who hate anyone who talks peace. They are not amenable to rational argument, so Dikaiopolis grabs a hostage and a sword and demands the old men leave him alone. The hostage is a basket of Acharnian charcoal, but the old men have a sentimental spot for anything from Acharnia (or maybe they are simply caught up in the drama of the moment), and they agree to leave Dikaiopolis in peace if only he will spare the charcoal. The importance of both the charcoal and the tool that Dikaiopolis holds hostage is that one of the primary sources of revenue for that region was the manufacturing and selling of charcoal. This is further justification for the dissenters' exaggerated response. He surrenders the hostage, but he now wants more than just to be left alone in peace: he desperately wants the old men to believe in the justice of his cause. He even says that he is willing to speak with his head on a chopping block, if only they will hear him out, and yet he knows how unpredictable his fellow citizens can be: he says he hasn't forgotten how Cleon dragged him into court over "last year's play."
This mention of trouble with Cleon over a play indicates that Dikaiopolis represents Aristophanes (or possibly his producer, Callistratus),[4] and maybe the author is in fact the actor behind the mask.[5] After gaining the chorus's permission for an anti-war speech, Dikaiopolis/Aristophanes decides he needs some special help with it, and he goes next door to the house of Euripides, an author renowned for his clever arguments. As it turns out, however, he merely goes there to borrow a costume from one of his tragedies, Telephus, in which the hero disguises himself as a beggar. Thus attired as a tragic hero disguised as a beggar, and with his head on the chopping block, Dikaiopolis/Telephus/the beggar/Aristophanes explains to the Chorus his reasons for opposing the war. The war all started, he argues, because of the abduction of three courtesans, and it is continued by profiteers for personal gain. Half the Chorus is won over by this argument, the other half isn't.
A fight breaks out between Acharnians for and Acharnians against Dikaiopolis/Telephus/the beggar/Aristophanes, and it only ends when the Athenian general Lamachus (who also happens to live next door) emerges from his house and imposes himself vaingloriously on the fray. Order is restored, and the general is then questioned by the hero about the reason why he personally supports the war against Sparta. Is it out of his sense of duty, or because he gets paid? This time the whole Chorus is won over by the arguments of Dikaiopolis. Dikaiopolis and Lamachus retire to their separate houses, and there then follows a parabasis in which the Chorus first lavishes exaggerated praise upon the author and next laments the ill treatment that old men like themselves suffer at the hands of slick lawyers in these fast times.
Dikaiopolis returns to the stage and sets up a private market where he and the enemies of Athens can trade peacefully. Various minor characters come and go in farcical circumstances. A starving Megarian trades his famished daughters, disguised as piglets, for garlic and salt (products in which Megara had abounded in pre-war days). Then an informer or sycophant tries to confiscate the piglets as enemy contraband before he is driven off by Dikaiopolis. (Note that piglets meant also female genitals).[6] Next, a Boeotian arrives with birds and eels for sale. Dikaiopolis has nothing to trade that the Boeotian could want, but he cleverly manages to interest him in a commodity that is rare in Boeotia – an Athenian sycophant. Another sycophant happens to arrive at that very moment, and he tries to confiscate the birds and eels, but instead he is packed in straw like a piece of pottery and carried off back home by the Boeotian.
Some other visitors come and go before two heralds arrive, one calling Lamachus to war, the other calling Dikaiopolis to a dinner party. The two men go as summoned and return soon after: Lamachus, in pain from injuries sustained in battle and with a soldier at each arm propping him up; Dikaiopolis, merrily drunk and with a dancing girl on each arm. Dikaiopolis clamors cheerfully for a wine skin – a prize awarded to him in a drinking competition – and then everyone exits in general celebrations (except Lamachus, who exits in pain).
