Dublin in the early 1920s, during the Irish Civil War period.
Juno and the Paycock concerns the Boyle family, who live in the Dublin tenements. The father, "Captain" Jack Boyle (so called because of his status as a retired merchant seaman, his propensity for telling colourful stories of the sea, and his incessant wearing of his nautical-looking hat) constantly tries to evade work by pretending to have pains in his legs, and spends all his money at the pub with his ne'er-do-well "butty", Joxer Daly. The mother, Juno, is the only member of the family working, as the daughter Mary is on strike, and the son, Johnny, lost his arm in the War of Independence. Johnny betrayed Tancred, a neighbour and fellow comrade in the IRA, and is afraid that he will be executed as punishment. A distant relative dies, and an English solicitor, Mr Bentham, brings news that the family has come into an inheritance. The family buys goods on credit, and borrows money from neighbours with the intent of paying them back when the fortune arrives. They hold a party during Tancred's funeral procession, halting it only when Tancred's aged mother passes by their door.
In the third act tragedy befalls the Boyle family. Mr Bentham, who had been courting Mary, ceases all contact with the family, and it becomes apparent that no money will be forthcoming. As the goods bought with the borrowed money are being taken back, Mr and Mrs Boyle learn that Mary has been impregnated by Mr Bentham. "Captain" Boyle goes with Joxer to a pub to spend the last of his money and take his mind off of the situation. While he is gone, Mrs Boyle learns that her son, Johnny, has been killed, presumably by the IRA. Mary and Juno leave to live with Juno's sister. Captain Boyle and Joxer return to the stage drunk.