Trying to catch Macheath, Mrs. Peachum enlists the help of Macheath’s former lover, the prostitute Jenny. She agrees to give up Macheath’s location for ten shillings and tells Mrs. Peachum that even if Macheath is trying to outwit the police, he will not give up his Thursday visit to the brothel. Mr. Peachum blackmails Brown into capturing Macheath by threatening that he will set his brood of beggars loose on the grounds of Buckingham Palace before the queen’s coronation on Friday. Trapped, Brown agrees to arrest his friend.
Jenny goes to Peachum’s office and demands her ten shillings. When Mrs. Peachum denies her payment because of Macheath’s escape, Jenny betrays his location once again, revealing that he is with the prostitute Suky Tawdry. Brown bursts in to arrest Peachum for threatening to set his beggars loose at the coronation. Brown orders the constables to arrest the beggars, but Peachum warns Brown that capturing them will disrupt the coronation, create a huge mess for the police, and ruin Brown’s reputation as sheriff. Prompted by Peachum, Jenny reveals Macheath’s location once again, and Brown calls an emergency conference of sergeants. Peachum sends the beggars to the jail, expecting that the police will capture Macheath.
Quickly discovered, Macheath is thrown back in jail and informed that he will be executed on Friday at six in the evening. Macheath attempts to bribe Smith with a thousand pounds, although a consultation with two of his fellow thieves reveals that only the sum of four hundred pounds is available. When Smith goes to fetch Macheath’s last meal, Polly and Brown enter with their apologies and last words and are soon joined by the rest of the characters. Macheath cries for mercy, but when the group reaches the gallows, a mounted messenger appears, bringing news that the queen has demanded the release of Macheath. As the crowd cheers, both Mr. and Mrs. Peachum address the audience, reminding them that happy endings do not happen in reality.