In a brief prologue, a ballad singer entertains a bustling crowd in the London neighborhood of Soho with a moritat, or murder ballad, about the exploits of the city’s slickest, most notorious gangster Macheath, or Mackie the Knife. At the end of the song, a well-dressed man in white gloves and spats slips away from the crowd. A prostitute named Ginny Jenny exclaims that Macheath has gotten away once again.
In Act One, Brecht introduces the audience to Jonathan Jeremiah Peachum—the owner of The Beggar’s Friend, an emporium where down-on-their-luck individuals seeking to break into begging can haggle with Peachum for a license to beg in one of London’s neighborhood and purchase dirty clothes, cardboard signs, and even faux stumps meant to give one the appearance of an amputee. After Peachum helps a young man named Filch pick out some beggar’s rags and stake a claim to one of the fourteen begging districts of London, Peachum’s wife, Mrs. Peachum, comes downstairs in a tizzy. She’s worried about their daughter Polly, who’s been spending all her time with a suitor known only as “the Captain.” As Mrs. Peachum describes the man to her husband, Peachum realizes the man his wife is describing is none other than Macheath. Elsewhere, in an empty stable, Macheath and Polly celebrate their elopement with a group of Macheath’s thugs. As the “wedding” celebration unfolds, Macheath demands entertainment and well wishes from his gang—but they offer only ribald jokes and halfhearted songs. The kind, generous Polly steps forward and sings a showstopping song about a barmaid who imagines herself to be a dangerous, vengeful pirate queen in order to cope with the cruel, thoughtless treatment she receives from her customers. At the end of the number, one of Macheath’s men bursts into the room and announces that the cops are on their way. Macheath is unbothered, and as the sheriff of London, Tiger Brown, steps into the room, the two men greet each other warmly. The two are old army buddies who have an arrangement in which Macheath pays Brown off to let his crimes go unsolved, while Brown warns Macheath whenever a raid is coming. Macheath nervously asks Brown whether Scotland Yard has any records on him, explaining that his new father-in-law won’t be happy about the marriage and might try to dig up some dirt on Mactheath. Brown assures Macheath he’s in the clear. The next day, Polly returns home to announce her marriage to her parents. Both Peachum and Mrs. Peachum chide Polly for throwing her life away. Polly begs her father to accept her love for Macheath, reminding him that Macheath can provide for her. Mrs. Peachum tries to get Polly to understand Macheath’s promiscuous nature by stating that if the man is ever hanged, half a dozen women will show up to mourn him. Peachum declares that a hanging is a great idea. Peachum and his wife come up with a plan to catch Macheath at his favorite brothel in Wapping and report him to the authorities. Polly insists Macheath would never cheat on her and warns her parents they’ll have trouble trumping up charges against the man. Peachum, however, declares that Macheath has broken the law in taking Polly from her home and having relations with her. As the Peachums approach the front of the stage to sing the Act 1 finale, they lament how rare happiness is, how base human beings are, and how the whole world is little more than a “heap of junk.”
In Act Two, Polly returns to the stable to warn Macheath that her father and Brown are plotting against him. Macheath is reluctant to flee, but when Polly produces a lengthy list of charges the police have against Macbeth—including statutory rape—he flies into a panic. Macheath orders his men to start moving money out of their accounts and makes plans to hide himself away in the countryside. Before leaving, he urges Polly to take good care of his business—and orders his men to listen to her and do whatever she asks of them. Polly worries that a portentous dream she had recently about the moon looking worn and thin signals Macheath’s infidelity, but Macheath promises he’ll always be true to Polly. Meanwhile, Mrs. Peachum meets with Ginny Jenny, who works at the brothel in Wapping. She urges Jenny to report any sighting of Macheath to the police. Jenny is skeptical that the newly-married Macheath will show his face in Wapping, but Mrs. Peachum declares that a man like Macheath can’t help himself when it comes to women. Later, Macheath arrives at the brothel, just as Mrs. Peachum predicted. Macheath and Jenny reunite and sing a song about their checkered past together—they used to be lovers, but Macheath would pimp Jenny out to other men and beat her when she didn’t earn enough. They nearly had a child together, but Jenny miscarried, and their relationship dissolved. While still singing, Jenny slips outside, where Mrs. Peachum is waiting with a policeman named Constable Smith. Macheath remains lost in his and Jenny’s duet, and doesn’t notice the police entering the establishment. Smith nabs Macheath. One of Macheath’s most loyal thugs, Hook-finger Jacob, runs off to alert the rest of the gang to their boss’s strife. Smith brings Macheath to the Old Bailey, where a nervous Tiger Brown is waiting to apologize to Macheath for his role in the man’s capture. Macheath wards Brown away with a punishing stare. As Macheath sits alone in his cell, Lucy Brown—Tiger’s daughter—enters and begins lambasting her “husband” for leaving her alone and pregnant. As Lucy and Macheath squabble, Polly enters—the two women, realizing that Macheath has double-timed them both, lob insults at one another. Macheath tries to calm both women down by professing his love for each of them. After Mrs. Peachum arrives to drag Polly away, Macheath promises Lucy he’ll send for her once he escapes. He asks her to fetch him his hat and walking stick, which conceals a large knife, off of a nearby hook. She obliges him, then departs. Smith arrives and enters Macheath’s cell to take back the weapon, but the armed Macheath seizes the opportunity to escape. Brown arrives and realizes what has happened. He becomes despondent over the authorities’ inability to catch Macheath. Peachum enters, asking for his reward—but finds the coppers embarrassed by their failure. Bemused, Peachum warns Brown that if he doesn’t catch Macheath soon, the new Queen of England—whose coronation is in just a couple days—will surely have her incompetent sheriff put to death. Macheath and Jenny step forward to sing the second-act finale, a song which describes how mankind must deny his humanity and turn to “mortal sin” just to survive.
In Act Three, Peachum organizes a gang of beggars whom he plans to have disrupt the coronation the following morning with a public protest. Ginny Jenny and several other prostitutes arrive, and Jenny demands her payment from Mrs. Peachum for her role in apprehending Macheath. Mrs. Peachum tells Jenny there’s no reward, as Macheath has escaped again. Jenny admits she knows that already—earlier that morning, Macheath visited her room, as well as the rooms of several other prostitutes. Rumor has it, she says, he’s now staying at the home of a prostitute named Suky Tawdry. Mrs. Peachum laments Macheath’s incorrigible nature. Filch enters and warns the Peachums that the police are nearby. Some of the beggars have instruments, and Peachum instructs them to begin playing when he says the word “harmless.” Tiger Brown enters, ready to arrest Peachum for his part in inciting a protest. Peachum chides the policeman for arresting an innocent man when real criminals are still on the loose. Brown, though, orders his men to arrest everyone in the establishment. Peachum tells Brown he’s more than welcome to arrest the “harmless” beggars. The band begins playing, and Peachum sings “The Song of the Futility of All Human Endeavor,” warning Brown that all his machinations will likely come to nothing. He reminds Brown how bad it’d look for the police to arrest innocent beggars—or to beat or obstruct them at the coronation parade the next day. Brown realizes his hands are tied. He orders his men to find Macheath and arrest him. Meanwhile, back at the Old Bailey, Lucy receives a visitor in her quarters—Polly Peachum. Polly begs Lucy’s forgiveness. The two women realize how much energy they’ve put into loving the no-good Macheath and decide to put aside their differences. Lucy reveals she’s not really pregnant, and says that when Macheath is found, Polly is free to have him to herself. The women hear voices outside—Macheath has been arrested again. The next morning, as the bells ring out five o’clock, Smith warns Macheath that he’s to be hung at six. Macheath attempts to bribe Smith, offering him a thousand pounds in exchange for release, but Smith says he doubts Macheath can get the money within the hour. Two of Macheath’s thugs, Money Matthew and Hook-finger Jacob, enter the hall and demand to see Macheath. Macheath begs the men to head to the bank and withdraw all that’s left in their gang’s account. The men tell Macheath they laundered the money away but will do their best to get what they can. A distraught Polly enters, fawning over Macheath’s bad fortune and professing her enduring love for him. Macheath, however, only asks Polly if she has any money. Polly breaks down in tears, and Smith drags her away. Tiger Brown enters with Macheath’s final meal and sits with his old friend as he eats it. Macheath offers to settle debts with the man—but when Brown actually takes out his ledger and begins tallying what Macheath owes, Macheath becomes enraged and lambasts Brown for repaying his years of friendship by sending him to the gallows. Brown, offended, calls for Smith to come lead Macheath to his execution. As Smith enters, he slyly reminds Macheath that there’s still time to escape—if he’s got the money. Macheath admits no one has been able to scrounge up the funds. Smith calls for the audience to Macheath’s hanging to enter the hall. Peachum, Mrs. Peachum, Polly, Lucy, Matthew, Jacob, Jenny, and many others flood the room and begin saying their tearful goodbyes to Macheath. Even those who professed to hate him are now sad to see him die. As the bells strike six, Macheath sings a song begging for mercy for them all—the outlaws, bandits, whores, burglars, pimps, and even detested coppers. Smith leads Macheath to the gallows, but as the man is strung up, Brown enters with a pardon from the Queen herself. The missive demands Macheath’s release, appoints him to the nobility, and grants him a castle and a pension for life. Everyone rejoices. Peachum reminds the audience that they’ve been watching a play—and that in plays, no one ever comes to the “generally bad” endings that exist in real life. The company comes together to sing a song which reminds the audience that the real world is nothing but a cold and lonely “vale of tribulation.”