Jungle of Cities is a play about a fight between two men, George Garga and Shlink. It takes place in the form of a boxing match, with each scene representing one round. Shlink is a wealthy lumber merchant at the start of the play and Garga is only a clerk in a book lending library.
The play opens with Shlink arriving at Maynes' lending library where Garga works. He is accompanied by accomplices, notably Skinny, The Worm, and The Baboon. He tries to buy Garga's opinion on a book, but Garga refuses to sell it. As a result, Shlink declares war on him and starts to destroy the bookshop. Maynes arrives and soon fires Garga. After Garga leaves, Shlink pays for the damage and departs.
Several weeks later Garga shows up in Shlink's office at the lumber yard. Shlink has decided to equalize the fight by giving Garga the lumber yard and making himself Garga's servant. Garga accepts the challenge and immediately makes the business sell the same lot of lumber twice, thereby cheating one of the buyers. He fires all of Shlink's staff and then pours ink onto the transaction ledger in order to ruin the business. Lastly, he invites a Salvation Army Officer into the room and promises to donate the entire building to him if the Officer will allow them to spit in his face. Shlink then goes over to the officer and spits at him.
Shlink goes to live in a Chinese Hotel owned by The Worm. Garga's sister Marie moves in with him, having fallen in love. Garga's girlfriend Jane is also there, working as a whore for The Baboon. Soon thereafter Garga decides to go away to Tahiti, leaving his family without anyone to provide them with money. Shlink arrives Garga's house and offers to work for them and provide them with money if they give him a place to stay. They readily agree to his proposal.
Although they all think that Garga has gone to Tahiti, it turns out that he never left Chicago. He soon goes to the hotel where Shlink is staying. When he learns that Marie is living there, he is upset that Shlink has taken over both his sister and his family. Garga starts to try to make Shlink marry Marie, but she becomes afraid and runs to Manky, who happily agrees to take her. Garga also makes Shlink give him all of his remaining money.
Marie returns to Shlink and tells him that Manky only had sex with her, but that there was no love. She is wretched at having lost her purity in such a mean fashion. Shlink gives her some money to help her.
Meanwhile, Garga has returned home and married his former girlfriend Jane after stealing her away from The Baboon. His family is living very nicely on the money that Shlink gave him. While celebrating the marriage dinner, Shlink arrives with a letter informing him that he will have to go to jail for three years for making a fraudulent lumber deal. Garga decides to go to jail instead even though it will destroy his family. When his mother hears this, she leaves the family. Garga writes a letter that accuses Shlink of raping his sister and violating his wife. He puts the letter into his pocket and tells his father that he will give the police the letter on the day that they release him from prison.
Three years later Garga gives the police the letter. Shlink is forced to flee from his new lumber yard that he has built during those years. Garga takes some men and visits the Chinese hotel in order to show them what has become of his sister and wife. Both Marie and Jane are now prostitutes in the hotel, and Jane refuses to even consider returning with Garga. Shlink manages to return to the hotel after setting fire to his lumber yard. He tells Garga that the fight is not yet over and that they need to flee immediately.
Three weeks later they end up in a tent used by railroad workers in the outskirts of Chicago. Garga realizes that the fight has been about trying to touch another person by hating them. It is a metaphysical form of contact. However, he decides that the fight has gone on too long. Garga proclaims himself the victor and leaves. Marie arrives and watches as Shlink dies in the tent. She defends his dead body from an angry mob that has arrived to lynch him.
Back in Chicago, Garga sells off the burnt down lumber yard. He sells it to Manky and makes Manky accept Marie and his father in the bargain. Garga pockets the money, having decided to go to New York. He remarks that the chaos of the fight was the best time he ever had.