June (Juno) is the wife of 'Captain' Boyle and the 'paycock' (or peacock) is her name for him, because he struts about all day, leaving her to work to put food on the table. He is called 'Captain' by his friends, but the nearest he has ever got to sailing is on the ferry to Liverpool.

Desperately poor, they live with their daughter Mary and son Johnny in a run-down Dublin tenement which also houses Boyle's drinking pal Joxer Daly, Maisie Madigan (who chatters incessantly), and Mrs. Tancred, whose son has been killed in an ambush. The city is caught up in the fight for Irish independence and violent death is a daily occurrence. Johnny supports the republican cause and has already lost an arm in the fighting at O'Connell Street, during the Easter rising of 1916.

Mary Boyle has two suitors - Jerry Devine, a young manual worker with political ambitions, and Charles Bentham, a solicitor, who has news for the family - they have been left some money by the Captain's cousin. Johnny, who has been sitting silently by the fire, immediately sees that the money might enable them to move somewhere else - somewhere they are not known. He is fearful of every knock at the door.

The Boyles decide to celebrate their good fortune. Their rooms are transformed with new furniture - all bought on credit. They have borrowed money too, on the strength of the legacy. Bentham is now an honoured guest in their home and officially engaged to Mary. They hold a party, but the jollity is disrupted when Johnny suddenly jumps up in distress and runs to the bedroom, where he claims to see a 'vision' of dead Robbie Tancred. Mrs Boyle manages to calm him.

Mrs. Madigan arrives and the party continues, until Mrs. Boyle hears Mrs. Tancred coming downstairs. Her son's body is being taken to the church.

Mrs. Boyle explains that Robbie and Johnny were once inseparable. The party becomes subdued again, but Boyle and Joxer set about raising everyone's spirits. Through the window comes the sound of hymn singing. Everyone goes to the window to see the procession pass - all except Johnny. It is Robbie Tancred's funeral procession. He was killed by an informer.

The partygoers decide they can get a better view of the procession downstairs. Johnny is left alone. A man in a trench coat appears at the door. He is surprised not to see Johnny at the funeral and tells him to report to his battalion. His superiors think he might know something about the man who informed on Tancred.

Time passes. Johnny comes and goes like a man on the run. Jerry Devine no longer visits. Bentham has gone away, leaving Mary downcast and worried. The creditors start to call. Boyle finally loses patience with the sly and devious Joxer. Mrs. Boyle thinks that Bentham has gone to England - leaving Mary pregnant. Boyle and Johnny are furious that Mary has brought this shame upon the family, but Juno says all they have to do is move to somewhere they are not known, with the money they received from the legacy. Boyle has to tell her and Johnny that there is no money - the will specified 'first cousin' rather than naming Boyle, and now 'first cousins' are appearing out of the woodwork.

Boyle is past caring. He makes it up with Joxer and spends the last few shillings he has on drink. As he leaves for the pub, Jerry Devine arrives, to offer Mary marriage and security, having heard that his rival is out of the way. Mary can hardly believe that Jerry would be so forgiving as to take her on, pregnant with another man's child. Then she realises - Jerry doesn't know. When it finally dawns on him, he is quick to change his mind. As he leaves, Mary sees the bailiff's men taking away the furniture.

Two men in trench coats arrive. They go up to the Boyle apartment, interrupting the furniture removers at their work. The men in trench coats produce guns and make the workmen turn to the wall. Claiming it was Johnny who informed on Tancred, they drag him from the house into a car and drive off.

When Juno returns everything has been taken from their rooms. Mrs. Madigan appears with the news that two policemen are waiting downstairs - some poor fellow has been found shot. Mrs. Boyle knows it is Johnny.

Juno and Mary decide to leave the tenement to make a new life for themselves and the baby. By the time a drunken Boyle and Joxer return to the stripped apartment, they have gone.